diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelper.java
index f217419..35c9bcb 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelper.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.btree.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndex;
@@ -31,25 +33,25 @@
 public class LSMBTreeDataflowHelper extends AbstractLSMIndexDataflowHelper {
 
     public LSMBTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, ILSMMergePolicy mergePolicy,
+            List<IVirtualBufferCache> virtualBufferCaches, ILSMMergePolicy mergePolicy,
             ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        this(opDesc, ctx, partition, virtualBufferCache, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
+        this(opDesc, ctx, partition, virtualBufferCaches, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
                 opTrackerFactory, ioScheduler, ioOpCallbackProvider);
     }
 
     public LSMBTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy,
+            List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy,
             ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(opDesc, ctx, partition, virtualBufferCache, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
+        super(opDesc, ctx, partition, virtualBufferCaches, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
                 ioScheduler, ioOpCallbackProvider);
     }
 
     @Override
     public ITreeIndex createIndexInstance() throws HyracksDataException {
         AbstractTreeIndexOperatorDescriptor treeOpDesc = (AbstractTreeIndexOperatorDescriptor) opDesc;
-        return LSMBTreeUtils.createLSMTree(virtualBufferCache, file, opDesc.getStorageManager().getBufferCache(ctx),
+        return LSMBTreeUtils.createLSMTree(virtualBufferCaches, file, opDesc.getStorageManager().getBufferCache(ctx),
                 opDesc.getStorageManager().getFileMapProvider(ctx), treeOpDesc.getTreeIndexTypeTraits(),
                 treeOpDesc.getTreeIndexComparatorFactories(), treeOpDesc.getTreeIndexBloomFilterKeyFields(),
                 bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory.getOperationTracker(ctx), ioScheduler,
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelperFactory.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelperFactory.java
index d331880..f4be88f 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelperFactory.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/dataflow/LSMBTreeDataflowHelperFactory.java
@@ -41,7 +41,7 @@
     public IndexDataflowHelper createIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
             int partition) {
         return new LSMBTreeDataflowHelper(opDesc, ctx, partition,
-                virtualBufferCacheProvider.getVirtualBufferCache(ctx), bloomFilterFalsePositiveRate,
+                virtualBufferCacheProvider.getVirtualBufferCaches(ctx), bloomFilterFalsePositiveRate,
                 mergePolicyProvider.getMergePolicy(ctx), opTrackerFactory, ioSchedulerProvider.getIOScheduler(ctx),
                 ioOpCallbackProvider);
     }
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
index 342faac..328629a 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.btree.impls;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
@@ -62,9 +63,11 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentSwitcherCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.freepage.VirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractLSMIndex;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractMutableLSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.BlockingIOOperationCallbackWrapper;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMTreeIndexAccessor;
@@ -75,7 +78,7 @@
 public class LSMBTree extends AbstractLSMIndex implements ITreeIndex {
 
     // In-memory components.
-    private final LSMBTreeMutableComponent mutableComponent;
+    private final List<LSMBTreeMutableComponent> mutableComponents;
 
     // For creating BTree's used in flush and merge.
     private final LSMBTreeImmutableComponentFactory componentFactory;
@@ -88,19 +91,43 @@
     private final ITreeIndexFrameFactory deleteLeafFrameFactory;
     private final IBinaryComparatorFactory[] cmpFactories;
 
-    public LSMBTree(IVirtualBufferCache virtualBufferCache, ITreeIndexFrameFactory interiorFrameFactory,
+    public LSMBTree(List<IVirtualBufferCache> virtualBufferCaches, ITreeIndexFrameFactory interiorFrameFactory,
             ITreeIndexFrameFactory insertLeafFrameFactory, ITreeIndexFrameFactory deleteLeafFrameFactory,
             ILSMIndexFileManager fileManager, TreeIndexFactory<BTree> diskBTreeFactory,
             TreeIndexFactory<BTree> bulkLoadBTreeFactory, BloomFilterFactory bloomFilterFactory,
             double bloomFilterFalsePositiveRate, IFileMapProvider diskFileMapProvider, int fieldCount,
             IBinaryComparatorFactory[] cmpFactories, ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(virtualBufferCache, diskBTreeFactory.getBufferCache(), fileManager, diskFileMapProvider,
+        super(virtualBufferCaches, diskBTreeFactory.getBufferCache(), fileManager, diskFileMapProvider,
                 bloomFilterFalsePositiveRate, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider);
-        mutableComponent = new LSMBTreeMutableComponent(new BTree(virtualBufferCache,
-                virtualBufferCache.getFileMapProvider(), new VirtualFreePageManager(virtualBufferCache.getNumPages()),
-                interiorFrameFactory, insertLeafFrameFactory, cmpFactories, fieldCount, new FileReference(new File(
-                        fileManager.getBaseDir() + "_virtual"))), virtualBufferCache);
+        mutableComponents = new ArrayList<LSMBTreeMutableComponent>();
+        final int numMutableComponents = virtualBufferCaches.size();
+        int i = 0;
+        for (IVirtualBufferCache virtualBufferCache : virtualBufferCaches) {
+            LSMBTreeMutableComponent mutableComponent = new LSMBTreeMutableComponent(new BTree(virtualBufferCache,
+                    virtualBufferCache.getFileMapProvider(), new VirtualFreePageManager(
+                            virtualBufferCache.getNumPages()), interiorFrameFactory, insertLeafFrameFactory,
+                    cmpFactories, fieldCount, new FileReference(new File(fileManager.getBaseDir() + "_virtual_" + i))),
+                    virtualBufferCache, i == 0 ? true : false);
+
+            mutableComponent.registerOnFlushCallback(new IMutableComponentSwitcherCallback() {
+
+                @Override
+                public void switchComponents() throws HyracksDataException {
+                    currentMutableComponentId.set((currentMutableComponentId.get() + 1) % numMutableComponents);
+                    mutableComponents.get(currentMutableComponentId.get()).setActive();
+                }
+
+                @Override
+                public void setFlushStatus(boolean isFlushNeeded) {
+                    needsFlush[currentMutableComponentId.get()].set(isFlushNeeded);
+                }
+            });
+
+            mutableComponents.add(mutableComponent);
+            ++i;
+        }
+
         this.insertLeafFrameFactory = insertLeafFrameFactory;
         this.deleteLeafFrameFactory = deleteLeafFrameFactory;
         this.cmpFactories = cmpFactories;
@@ -124,10 +151,11 @@
         if (isActivated) {
             throw new HyracksDataException("Failed to activate the index since it is already activated.");
         }
-
-        ((IVirtualBufferCache) mutableComponent.getBTree().getBufferCache()).open();
-        mutableComponent.getBTree().create();
-        mutableComponent.getBTree().activate();
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            ((IVirtualBufferCache) mutableComponent.getBTree().getBufferCache()).open();
+            mutableComponent.getBTree().create();
+            mutableComponent.getBTree().activate();
+        }
         List<ILSMComponent> immutableComponents = componentsRef.get();
         immutableComponents.clear();
         List<LSMComponentFileReferences> validFileReferences;
@@ -176,9 +204,11 @@
             btree.deactivate();
             bloomFilter.deactivate();
         }
-        mutableComponent.getBTree().deactivate();
-        mutableComponent.getBTree().destroy();
-        ((IVirtualBufferCache) mutableComponent.getBTree().getBufferCache()).close();
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getBTree().deactivate();
+            mutableComponent.getBTree().destroy();
+            ((IVirtualBufferCache) mutableComponent.getBTree().getBufferCache()).close();
+        }
         isActivated = false;
     }
 
@@ -199,7 +229,9 @@
             component.getBTree().destroy();
             component.getBloomFilter().destroy();
         }
-        mutableComponent.getBTree().destroy();
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getBTree().destroy();
+        }
         fileManager.deleteDirs();
     }
 
@@ -210,8 +242,10 @@
         }
 
         List<ILSMComponent> immutableComponents = componentsRef.get();
-        mutableComponent.getBTree().clear();
-        mutableComponent.reset();
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getBTree().clear();
+            mutableComponent.reset();
+        }
         for (ILSMComponent c : immutableComponents) {
             LSMBTreeImmutableComponent component = (LSMBTreeImmutableComponent) c;
             component.getBloomFilter().deactivate();
@@ -223,26 +257,33 @@
     }
 
     @Override
-    public ILSMComponent getMutableComponent() {
-        return mutableComponent;
-    }
-
-    @Override
     public void getOperationalComponents(ILSMIndexOperationContext ctx) {
         List<ILSMComponent> immutableComponents = componentsRef.get();
         List<ILSMComponent> operationalComponents = ctx.getComponentHolder();
         operationalComponents.clear();
+        int cmc = currentMutableComponentId.get();
+        ctx.setCurrentMutableComponentId(cmc);
+        int numMutableComponents = mutableComponents.size();
         switch (ctx.getOperation()) {
             case UPDATE:
             case UPSERT:
             case PHYSICALDELETE:
             case FLUSH:
             case DELETE:
-                operationalComponents.add(mutableComponent);
+                operationalComponents.add(mutableComponents.get(cmc));
                 break;
             case SEARCH:
             case INSERT:
-                operationalComponents.add(mutableComponent);
+                for (int i = 0; i < numMutableComponents - 1; i++) {
+                    LSMBTreeMutableComponent mutableComponent = mutableComponents.get((cmc + i + 1)
+                            % numMutableComponents);
+                    if (mutableComponent.isReadable()) {
+                        // Make sure newest components are added first
+                        operationalComponents.add(0, mutableComponent);
+                    }
+                }
+                // The current mutable component is always added
+                operationalComponents.add(0, mutableComponents.get(cmc));
                 operationalComponents.addAll(immutableComponents);
                 break;
             case MERGE:
@@ -258,27 +299,27 @@
         LSMBTreeOpContext ctx = (LSMBTreeOpContext) ictx;
         switch (ctx.getOperation()) {
             case PHYSICALDELETE:
-                ctx.memBTreeAccessor.delete(tuple);
+                ctx.currentMutableBTreeAccessor.delete(tuple);
                 break;
             case INSERT:
                 insert(tuple, ctx);
                 break;
             default:
-                ctx.memBTreeAccessor.upsert(tuple);
+                ctx.currentMutableBTreeAccessor.upsert(tuple);
                 break;
         }
-        mutableComponent.setIsModified();
+        mutableComponents.get(currentMutableComponentId.get()).setIsModified();
     }
 
     private boolean insert(ITupleReference tuple, LSMBTreeOpContext ctx) throws HyracksDataException, IndexException {
-        MultiComparator comparator = MultiComparator.createIgnoreFieldLength(mutableComponent.getBTree()
-                .getComparatorFactories());
+        MultiComparator comparator = MultiComparator.createIgnoreFieldLength(mutableComponents
+                .get(currentMutableComponentId.get()).getBTree().getComparatorFactories());
         LSMBTreePointSearchCursor searchCursor = new LSMBTreePointSearchCursor(ctx);
-        IIndexCursor memCursor = new BTreeRangeSearchCursor(ctx.memBTreeOpCtx.leafFrame, false);
+        IIndexCursor memCursor = new BTreeRangeSearchCursor(ctx.currentMutableBTreeOpCtx.leafFrame, false);
         RangePredicate predicate = new RangePredicate(tuple, tuple, true, true, comparator, comparator);
 
         // first check the inmemory component
-        ctx.memBTreeAccessor.search(memCursor, predicate);
+        ctx.currentMutableBTreeAccessor.search(memCursor, predicate);
         try {
             if (memCursor.hasNext()) {
                 memCursor.next();
@@ -287,7 +328,8 @@
                     throw new TreeIndexDuplicateKeyException("Failed to insert key since key already exists.");
                 } else {
                     memCursor.close();
-                    ctx.memBTreeAccessor.upsertIfConditionElseInsert(tuple, AntimatterAwareTupleAcceptor.INSTANCE);
+                    ctx.currentMutableBTreeAccessor.upsertIfConditionElseInsert(tuple,
+                            AntimatterAwareTupleAcceptor.INSTANCE);
                     return true;
                 }
             }
@@ -301,6 +343,9 @@
         // the mutable component?
         // the key was not in the inmemory component, so check the disk
         // components
+
+        // This is a hack to avoid searching the current active mutable component twice. It is critical to add it back once the search is over.
+        ILSMComponent c = ctx.getComponentHolder().remove(0);
         search(ctx, searchCursor, predicate);
         try {
             if (searchCursor.hasNext()) {
@@ -308,9 +353,11 @@
             }
         } finally {
             searchCursor.close();
+            // Add the current active mutable component back
+            ctx.getComponentHolder().add(0, c);
         }
-        ctx.memBTreeAccessor.upsertIfConditionElseInsert(tuple, AntimatterAwareTupleAcceptor.INSTANCE);
 
+        ctx.currentMutableBTreeAccessor.upsertIfConditionElseInsert(tuple, AntimatterAwareTupleAcceptor.INSTANCE);
         return true;
     }
 
@@ -319,26 +366,22 @@
             throws HyracksDataException, IndexException {
         LSMBTreeOpContext ctx = (LSMBTreeOpContext) ictx;
         List<ILSMComponent> operationalComponents = ctx.getComponentHolder();
-        int numBTrees = operationalComponents.size();
-        assert numBTrees > 0;
 
-        boolean includeMutableComponent = operationalComponents.get(0) == mutableComponent;
-        LSMBTreeCursorInitialState initialState = new LSMBTreeCursorInitialState(numBTrees, insertLeafFrameFactory,
-                ctx.cmp, ctx.bloomFilterCmp, includeMutableComponent, lsmHarness, ctx.memBTreeAccessor, pred,
-                ctx.searchCallback, operationalComponents);
+        LSMBTreeCursorInitialState initialState = new LSMBTreeCursorInitialState(insertLeafFrameFactory, ctx.cmp,
+                ctx.bloomFilterCmp, lsmHarness, pred, ctx.searchCallback, operationalComponents);
         cursor.open(initialState, pred);
     }
 
     @Override
     public boolean scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        if (!mutableComponent.isModified()) {
+        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
+        if (!((AbstractMutableLSMComponent) flushingComponent).isModified()) {
             return false;
         }
         LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
         LSMBTreeOpContext opCtx = createOpContext(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
         assert ctx.getComponentHolder().size() == 1;
-        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
         opCtx.setOperation(IndexOperation.FLUSH);
         opCtx.getComponentHolder().add(flushingComponent);
         ILSMIndexAccessorInternal flushAccessor = new LSMBTreeAccessor(lsmHarness, opCtx);
@@ -576,7 +619,7 @@
 
     public LSMBTreeOpContext createOpContext(IModificationOperationCallback modificationCallback,
             ISearchOperationCallback searchCallback) {
-        return new LSMBTreeOpContext(mutableComponent.getBTree(), insertLeafFrameFactory, deleteLeafFrameFactory,
+        return new LSMBTreeOpContext(mutableComponents, insertLeafFrameFactory, deleteLeafFrameFactory,
                 modificationCallback, searchCallback, componentFactory.getBloomFilterKeyFields().length);
     }
 
@@ -613,47 +656,60 @@
 
     @Override
     public ITreeIndexFrameFactory getInteriorFrameFactory() {
-        return mutableComponent.getBTree().getInteriorFrameFactory();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getInteriorFrameFactory();
     }
 
     @Override
     public int getFieldCount() {
-        return mutableComponent.getBTree().getFieldCount();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getFieldCount();
     }
 
     @Override
     public int getFileId() {
-        return mutableComponent.getBTree().getFileId();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getFileId();
     }
 
     @Override
     public IFreePageManager getFreePageManager() {
-        return mutableComponent.getBTree().getFreePageManager();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getFreePageManager();
     }
 
     @Override
     public ITreeIndexFrameFactory getLeafFrameFactory() {
-        return mutableComponent.getBTree().getLeafFrameFactory();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getLeafFrameFactory();
     }
 
     @Override
     public long getMemoryAllocationSize() {
-        IBufferCache virtualBufferCache = mutableComponent.getBTree().getBufferCache();
-        return virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        long size = 0;
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            IBufferCache virtualBufferCache = mutableComponent.getBTree().getBufferCache();
+            size += virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        }
+        return size;
     }
 
     @Override
     public int getRootPageId() {
-        return mutableComponent.getBTree().getRootPageId();
+        return mutableComponents.get(currentMutableComponentId.get()).getBTree().getRootPageId();
     }
 
     public boolean isEmptyIndex() throws HyracksDataException {
-        return componentsRef.get().isEmpty() && !mutableComponent.isModified();
+        boolean isModified = false;
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            if (mutableComponent.isModified()) {
+                isModified = true;
+                break;
+            }
+        }
+        return componentsRef.get().isEmpty() && !isModified;
     }
 
     @Override
     public void validate() throws HyracksDataException {
-        mutableComponent.getBTree().validate();
+        for (LSMBTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getBTree().validate();
+        }
         List<ILSMComponent> immutableComponents = componentsRef.get();
         for (ILSMComponent c : immutableComponents) {
             BTree btree = (BTree) ((LSMBTreeImmutableComponent) c).getBTree();
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeCursorInitialState.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeCursorInitialState.java
index b5c6a45..37f89ff 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeCursorInitialState.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeCursorInitialState.java
@@ -18,7 +18,6 @@
 import java.util.List;
 
 import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
-import edu.uci.ics.hyracks.storage.am.common.api.IIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrameFactory;
@@ -29,39 +28,28 @@
 
 public class LSMBTreeCursorInitialState implements ICursorInitialState {
 
-    private final int numBTrees;
     private final ITreeIndexFrameFactory leafFrameFactory;
     private MultiComparator cmp;
     private final MultiComparator bloomFilterCmp;
-    private final boolean includeMemComponent;
     private final ILSMHarness lsmHarness;
 
-    private final IIndexAccessor memBtreeAccessor;
     private final ISearchPredicate predicate;
     private ISearchOperationCallback searchCallback;
 
     private final List<ILSMComponent> operationalComponents;
 
-    public LSMBTreeCursorInitialState(int numBTrees, ITreeIndexFrameFactory leafFrameFactory, MultiComparator cmp,
-            MultiComparator bloomFilterCmp, boolean includeMemComponent, ILSMHarness lsmHarness,
-            IIndexAccessor memBtreeAccessor, ISearchPredicate predicate, ISearchOperationCallback searchCallback,
-            List<ILSMComponent> operationalComponents) {
-        this.numBTrees = numBTrees;
+    public LSMBTreeCursorInitialState(ITreeIndexFrameFactory leafFrameFactory, MultiComparator cmp,
+            MultiComparator bloomFilterCmp, ILSMHarness lsmHarness, ISearchPredicate predicate,
+            ISearchOperationCallback searchCallback, List<ILSMComponent> operationalComponents) {
         this.leafFrameFactory = leafFrameFactory;
         this.cmp = cmp;
         this.bloomFilterCmp = bloomFilterCmp;
-        this.includeMemComponent = includeMemComponent;
         this.lsmHarness = lsmHarness;
         this.searchCallback = searchCallback;
-        this.memBtreeAccessor = memBtreeAccessor;
         this.predicate = predicate;
         this.operationalComponents = operationalComponents;
     }
 
-    public int getNumBTrees() {
-        return numBTrees;
-    }
-
     public ITreeIndexFrameFactory getLeafFrameFactory() {
         return leafFrameFactory;
     }
@@ -75,10 +63,6 @@
     public void setPage(ICachedPage page) {
     }
 
-    public boolean getIncludeMemComponent() {
-        return includeMemComponent;
-    }
-
     public ILSMHarness getLSMHarness() {
         return lsmHarness;
     }
@@ -97,10 +81,6 @@
         return operationalComponents;
     }
 
-    public IIndexAccessor getMemBTreeAccessor() {
-        return memBtreeAccessor;
-    }
-
     public ISearchPredicate getSearchPredicate() {
         return predicate;
     }
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMutableComponent.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMutableComponent.java
index 6c01b29..c0605e5 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMutableComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMutableComponent.java
@@ -24,8 +24,8 @@
 
     private final BTree btree;
 
-    public LSMBTreeMutableComponent(BTree btree, IVirtualBufferCache vbc) {
-        super(vbc);
+    public LSMBTreeMutableComponent(BTree btree, IVirtualBufferCache vbc, boolean isActive) {
+        super(vbc, isActive);
         this.btree = btree;
     }
 
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeOpContext.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeOpContext.java
index ac62d9f..036c306 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeOpContext.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeOpContext.java
@@ -37,9 +37,11 @@
     public ITreeIndexFrameFactory deleteLeafFrameFactory;
     public IBTreeLeafFrame insertLeafFrame;
     public IBTreeLeafFrame deleteLeafFrame;
-    public final BTree memBTree;
-    public BTree.BTreeAccessor memBTreeAccessor;
-    public BTreeOpContext memBTreeOpCtx;
+    public final BTree[] mutableBTrees;
+    public BTree.BTreeAccessor[] mutableBTreeAccessors;
+    public BTreeOpContext[] mutableBTreeOpCtxs;
+    public BTree.BTreeAccessor currentMutableBTreeAccessor;
+    public BTreeOpContext currentMutableBTreeOpCtx;
     public IndexOperation op;
     public final MultiComparator cmp;
     public final MultiComparator bloomFilterCmp;
@@ -47,19 +49,30 @@
     public final ISearchOperationCallback searchCallback;
     private final List<ILSMComponent> componentHolder;
 
-    public LSMBTreeOpContext(BTree memBTree, ITreeIndexFrameFactory insertLeafFrameFactory,
-            ITreeIndexFrameFactory deleteLeafFrameFactory, IModificationOperationCallback modificationCallback,
-            ISearchOperationCallback searchCallback, int numBloomFilterKeyFields) {
-        IBinaryComparatorFactory cmpFactories[] = memBTree.getComparatorFactories();
+    public LSMBTreeOpContext(List<LSMBTreeMutableComponent> mutableComponents,
+            ITreeIndexFrameFactory insertLeafFrameFactory, ITreeIndexFrameFactory deleteLeafFrameFactory,
+            IModificationOperationCallback modificationCallback, ISearchOperationCallback searchCallback,
+            int numBloomFilterKeyFields) {
+        IBinaryComparatorFactory cmpFactories[] = mutableComponents.get(0).getBTree().getComparatorFactories();
         if (cmpFactories[0] != null) {
-            this.cmp = MultiComparator.create(memBTree.getComparatorFactories());
+            this.cmp = MultiComparator.create(mutableComponents.get(0).getBTree().getComparatorFactories());
         } else {
             this.cmp = null;
         }
 
-        bloomFilterCmp = MultiComparator.create(memBTree.getComparatorFactories(), 0, numBloomFilterKeyFields);
+        bloomFilterCmp = MultiComparator.create(mutableComponents.get(0).getBTree().getComparatorFactories(), 0,
+                numBloomFilterKeyFields);
 
-        this.memBTree = memBTree;
+        mutableBTrees = new BTree[mutableComponents.size()];
+        mutableBTreeAccessors = new BTree.BTreeAccessor[mutableComponents.size()];
+        mutableBTreeOpCtxs = new BTreeOpContext[mutableComponents.size()];
+        for (int i = 0; i < mutableComponents.size(); i++) {
+            mutableBTrees[i] = mutableComponents.get(i).getBTree();
+            mutableBTreeAccessors[i] = (BTree.BTreeAccessor) mutableBTrees[i].createAccessor(modificationCallback,
+                    NoOpOperationCallback.INSTANCE);
+            mutableBTreeOpCtxs[i] = mutableBTreeAccessors[i].getOpContext();
+        }
+
         this.insertLeafFrameFactory = insertLeafFrameFactory;
         this.deleteLeafFrameFactory = deleteLeafFrameFactory;
         this.insertLeafFrame = (IBTreeLeafFrame) insertLeafFrameFactory.createFrame();
@@ -79,48 +92,16 @@
     public void setOperation(IndexOperation newOp) {
         reset();
         this.op = newOp;
-        switch (newOp) {
-            case SEARCH:
-                setMemBTreeAccessor();
-                break;
-            case DISKORDERSCAN:
-            case UPDATE:
-                // Attention: It is important to leave the leafFrame and
-                // leafFrameFactory of the memBTree as is when doing an update.
-                // Update will only be set if a previous attempt to delete or
-                // insert failed, so we must preserve the semantics of the
-                // previously requested operation.
-                setMemBTreeAccessor();
-                return;
-            case UPSERT:
-            case INSERT:
-                setInsertMode();
-                break;
-            case PHYSICALDELETE:
-            case DELETE:
-                setDeleteMode();
-                break;
-        }
-    }
-
-    private void setMemBTreeAccessor() {
-        if (memBTreeAccessor == null) {
-            memBTreeAccessor = (BTree.BTreeAccessor) memBTree.createAccessor(modificationCallback,
-                    NoOpOperationCallback.INSTANCE);
-            memBTreeOpCtx = memBTreeAccessor.getOpContext();
-        }
     }
 
     public void setInsertMode() {
-        setMemBTreeAccessor();
-        memBTreeOpCtx.leafFrame = insertLeafFrame;
-        memBTreeOpCtx.leafFrameFactory = insertLeafFrameFactory;
+        currentMutableBTreeOpCtx.leafFrame = insertLeafFrame;
+        currentMutableBTreeOpCtx.leafFrameFactory = insertLeafFrameFactory;
     }
 
     public void setDeleteMode() {
-        setMemBTreeAccessor();
-        memBTreeOpCtx.leafFrame = deleteLeafFrame;
-        memBTreeOpCtx.leafFrameFactory = deleteLeafFrameFactory;
+        currentMutableBTreeOpCtx.leafFrame = deleteLeafFrame;
+        currentMutableBTreeOpCtx.leafFrameFactory = deleteLeafFrameFactory;
     }
 
     @Override
@@ -146,4 +127,30 @@
     public IModificationOperationCallback getModificationCallback() {
         return modificationCallback;
     }
+
+    @Override
+    public void setCurrentMutableComponentId(int currentMutableComponentId) {
+        currentMutableBTreeAccessor = mutableBTreeAccessors[currentMutableComponentId];
+        currentMutableBTreeOpCtx = mutableBTreeOpCtxs[currentMutableComponentId];
+        switch (op) {
+            case SEARCH:
+                break;
+            case DISKORDERSCAN:
+            case UPDATE:
+                // Attention: It is important to leave the leafFrame and
+                // leafFrameFactory of the mutableBTree as is when doing an update.
+                // Update will only be set if a previous attempt to delete or
+                // insert failed, so we must preserve the semantics of the
+                // previously requested operation.
+                break;
+            case UPSERT:
+            case INSERT:
+                setInsertMode();
+                break;
+            case PHYSICALDELETE:
+            case DELETE:
+                setDeleteMode();
+                break;
+        }
+    }
 }
\ No newline at end of file
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreePointSearchCursor.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreePointSearchCursor.java
index 64e0c28..005629f 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreePointSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreePointSearchCursor.java
@@ -15,7 +15,7 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.btree.impls;
 
-import java.util.ListIterator;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
@@ -32,6 +32,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent.LSMComponentType;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMHarness;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMTreeTupleReference;
@@ -45,14 +46,14 @@
     private final ILSMIndexOperationContext opCtx;
     private ISearchOperationCallback searchCallback;
     private RangePredicate predicate;
-    private IIndexAccessor memBTreeAccessor;
-    private boolean includeMemComponent;
+    private boolean includeMutableComponent;
     private int numBTrees;
-    private IIndexAccessor[] bTreeAccessors;
+    private IIndexAccessor[] btreeAccessors;
     private ILSMHarness lsmHarness;
     private boolean nextHasBeenCalled;
     private boolean foundTuple;
     private ITupleReference frameTuple;
+    private List<ILSMComponent> operationalComponents;
 
     public LSMBTreePointSearchCursor(ILSMIndexOperationContext opCtx) {
         this.opCtx = opCtx;
@@ -67,7 +68,7 @@
         }
         boolean reconciled = false;
         for (int i = 0; i < numBTrees; ++i) {
-            bTreeAccessors[i].search(rangeCursors[i], predicate);
+            btreeAccessors[i].search(rangeCursors[i], predicate);
             if (rangeCursors[i].hasNext()) {
                 rangeCursors[i].next();
                 // We use the predicate's to lock the key instead of the tuple that we get from cursor to avoid copying the tuple when we do the "unlatch dance"
@@ -83,14 +84,14 @@
                         return true;
                     }
                 }
-                if (i == 0 && includeMemComponent) {
+                if (i == 0 && includeMutableComponent) {
                     // unlatch/unpin
                     rangeCursors[i].reset();
                     searchCallback.reconcile(predicate.getLowKey());
                     reconciled = true;
 
                     // retraverse
-                    memBTreeAccessor.search(rangeCursors[i], predicate);
+                    btreeAccessors[0].search(rangeCursors[i], predicate);
                     searchCallback.complete(predicate.getLowKey());
                     if (rangeCursors[i].hasNext()) {
                         rangeCursors[i].next();
@@ -123,14 +124,14 @@
     @Override
     public void reset() throws HyracksDataException, IndexException {
         try {
-        if (rangeCursors != null) {
-            for (int i = 0; i < rangeCursors.length; ++i) {
-                rangeCursors[i].reset();
+            if (rangeCursors != null) {
+                for (int i = 0; i < rangeCursors.length; ++i) {
+                    rangeCursors[i].reset();
+                }
             }
-        }
-        rangeCursors = null;
-        nextHasBeenCalled = false;
-        foundTuple = false;
+            rangeCursors = null;
+            nextHasBeenCalled = false;
+            foundTuple = false;
         } finally {
             if (lsmHarness != null) {
                 lsmHarness.endSearch(opCtx);
@@ -141,41 +142,30 @@
     @Override
     public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException {
         LSMBTreeCursorInitialState lsmInitialState = (LSMBTreeCursorInitialState) initialState;
-        includeMemComponent = lsmInitialState.getIncludeMemComponent();
+        operationalComponents = lsmInitialState.getOperationalComponents();
         lsmHarness = lsmInitialState.getLSMHarness();
         searchCallback = lsmInitialState.getSearchOperationCallback();
-        memBTreeAccessor = lsmInitialState.getMemBTreeAccessor();
         predicate = (RangePredicate) lsmInitialState.getSearchPredicate();
-
-        numBTrees = lsmInitialState.getNumBTrees();
+        numBTrees = operationalComponents.size();
         rangeCursors = new IIndexCursor[numBTrees];
-        int i = 0;
-        if (includeMemComponent) {
-            // No need for a bloom filter for the in-memory BTree.
-            IBTreeLeafFrame leafFrame = (IBTreeLeafFrame) lsmInitialState.getLeafFrameFactory().createFrame();
-            rangeCursors[i] = new BTreeRangeSearchCursor(leafFrame, false);
-            ++i;
-        }
-        for (; i < numBTrees; ++i) {
-            IBTreeLeafFrame leafFrame = (IBTreeLeafFrame) lsmInitialState.getLeafFrameFactory().createFrame();
-            rangeCursors[i] = new BloomFilterAwareBTreePointSearchCursor(leafFrame, false,
-                    ((LSMBTreeImmutableComponent) lsmInitialState.getOperationalComponents().get(i)).getBloomFilter());
-        }
+        btreeAccessors = new IIndexAccessor[numBTrees];
+        includeMutableComponent = false;
 
-        bTreeAccessors = new IIndexAccessor[numBTrees];
-        int cursorIx = 0;
-        ListIterator<ILSMComponent> btreesIter = lsmInitialState.getOperationalComponents().listIterator();
-        if (includeMemComponent) {
-            bTreeAccessors[cursorIx] = memBTreeAccessor;
-            ++cursorIx;
-            btreesIter.next();
-        }
-
-        while (btreesIter.hasNext()) {
-            BTree diskBTree = ((LSMBTreeImmutableComponent) btreesIter.next()).getBTree();
-            bTreeAccessors[cursorIx] = diskBTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            cursorIx++;
+        for (int i = 0; i < numBTrees; i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            BTree btree;
+            IBTreeLeafFrame leafFrame = (IBTreeLeafFrame) lsmInitialState.getLeafFrameFactory().createFrame();
+            if (component.getType() == LSMComponentType.MEMORY) {
+                includeMutableComponent = true;
+                // No need for a bloom filter for the in-memory BTree.
+                rangeCursors[i] = new BTreeRangeSearchCursor(leafFrame, false);
+                btree = (BTree) ((LSMBTreeMutableComponent) component).getBTree();
+            } else {
+                rangeCursors[i] = new BloomFilterAwareBTreePointSearchCursor(leafFrame, false,
+                        ((LSMBTreeImmutableComponent) component).getBloomFilter());
+                btree = (BTree) ((LSMBTreeImmutableComponent) component).getBTree();
+            }
+            btreeAccessors[i] = btree.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
         }
         nextHasBeenCalled = false;
         foundTuple = false;
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeRangeSearchCursor.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeRangeSearchCursor.java
index 4bdebae..d832583 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeRangeSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeRangeSearchCursor.java
@@ -16,7 +16,6 @@
 package edu.uci.ics.hyracks.storage.am.lsm.btree.impls;
 
 import java.util.Iterator;
-import java.util.ListIterator;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.dataflow.common.comm.io.ArrayTupleBuilder;
@@ -35,6 +34,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent.LSMComponentType;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMIndexSearchCursor;
 
@@ -44,7 +44,7 @@
 
     private ISearchOperationCallback searchCallback;
     private RangePredicate predicate;
-    private IIndexAccessor memBTreeAccessor;
+    private IIndexAccessor[] btreeAccessors;
     private ArrayTupleBuilder tupleBuilder;
     private boolean proceed = true;
 
@@ -72,25 +72,25 @@
             if (!outputPriorityQueue.isEmpty()) {
                 PriorityQueueElement checkElement = outputPriorityQueue.peek();
                 if (proceed && !searchCallback.proceed(checkElement.getTuple())) {
-                    if (includeMemComponent) {
-                        PriorityQueueElement inMemElement = null;
-                        boolean inMemElementFound = false;
-                        // scan the PQ for the in-memory component's element
+                    if (includeMutableComponent) {
+                        PriorityQueueElement mutableElement = null;
+                        boolean mutableElementFound = false;
+                        // scan the PQ for the mutable component's element
                         Iterator<PriorityQueueElement> it = outputPriorityQueue.iterator();
                         while (it.hasNext()) {
-                            inMemElement = it.next();
-                            if (inMemElement.getCursorIndex() == 0) {
-                                inMemElementFound = true;
+                            mutableElement = it.next();
+                            if (mutableElement.getCursorIndex() == 0) {
+                                mutableElementFound = true;
                                 it.remove();
                                 break;
                             }
                         }
-                        if (inMemElementFound) {
+                        if (mutableElementFound) {
                             // copy the in-mem tuple
                             if (tupleBuilder == null) {
                                 tupleBuilder = new ArrayTupleBuilder(cmp.getKeyFieldCount());
                             }
-                            TupleUtils.copyTuple(tupleBuilder, inMemElement.getTuple(), cmp.getKeyFieldCount());
+                            TupleUtils.copyTuple(tupleBuilder, mutableElement.getTuple(), cmp.getKeyFieldCount());
                             copyTuple.reset(tupleBuilder.getFieldEndOffsets(), tupleBuilder.getByteArray());
 
                             // unlatch/unpin
@@ -105,11 +105,11 @@
                             }
                             // retraverse
                             reusablePred.setLowKey(copyTuple, true);
-                            memBTreeAccessor.search(rangeCursors[0], reusablePred);
-                            boolean isNotExhaustedCursor = pushIntoPriorityQueue(inMemElement);
-                            
+                            btreeAccessors[0].search(rangeCursors[0], reusablePred);
+                            boolean isNotExhaustedCursor = pushIntoPriorityQueue(mutableElement);
+
                             if (checkElement.getCursorIndex() == 0) {
-                                if (!isNotExhaustedCursor || cmp.compare(copyTuple, inMemElement.getTuple()) != 0) {
+                                if (!isNotExhaustedCursor || cmp.compare(copyTuple, mutableElement.getTuple()) != 0) {
                                     searchCallback.complete(copyTuple);
                                     searchCallback.cancel(copyTuple);
                                     continue;
@@ -117,7 +117,7 @@
                                 searchCallback.complete(copyTuple);
                             }
                         } else {
-                            // the in-memory cursor is exhausted
+                            // the mutable cursor is exhausted
                             searchCallback.reconcile(checkElement.getTuple());
                         }
                     } else {
@@ -174,46 +174,34 @@
             IndexException {
         LSMBTreeCursorInitialState lsmInitialState = (LSMBTreeCursorInitialState) initialState;
         cmp = lsmInitialState.getOriginalKeyComparator();
-        includeMemComponent = lsmInitialState.getIncludeMemComponent();
         operationalComponents = lsmInitialState.getOperationalComponents();
         lsmHarness = lsmInitialState.getLSMHarness();
         searchCallback = lsmInitialState.getSearchOperationCallback();
-        memBTreeAccessor = lsmInitialState.getMemBTreeAccessor();
         predicate = (RangePredicate) lsmInitialState.getSearchPredicate();
         reusablePred.setLowKeyComparator(cmp);
         reusablePred.setHighKey(predicate.getHighKey(), predicate.isHighKeyInclusive());
         reusablePred.setHighKeyComparator(predicate.getHighKeyComparator());
+        includeMutableComponent = false;
 
-        int numBTrees = lsmInitialState.getNumBTrees();
+        int numBTrees = operationalComponents.size();
         rangeCursors = new IIndexCursor[numBTrees];
+
+        btreeAccessors = new ITreeIndexAccessor[numBTrees];
         for (int i = 0; i < numBTrees; i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            BTree btree;
             IBTreeLeafFrame leafFrame = (IBTreeLeafFrame) lsmInitialState.getLeafFrameFactory().createFrame();
             rangeCursors[i] = new BTreeRangeSearchCursor(leafFrame, false);
+            if (component.getType() == LSMComponentType.MEMORY) {
+                includeMutableComponent = true;
+                btree = (BTree) ((LSMBTreeMutableComponent) component).getBTree();
+            } else {
+                btree = (BTree) ((LSMBTreeImmutableComponent) component).getBTree();
+            }
+            btreeAccessors[i] = btree.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            btreeAccessors[i].search(rangeCursors[i], searchPred);
         }
         setPriorityQueueComparator();
-
-        int cursorIx = 0;
-        ListIterator<ILSMComponent> btreesIter = operationalComponents.listIterator();
-        if (includeMemComponent) {
-            // Open cursor of in-memory BTree at index 0.
-            memBTreeAccessor.search(rangeCursors[cursorIx], searchPred);
-            // Skip 0 because it is the in-memory BTree.
-            ++cursorIx;
-            btreesIter.next();
-        }
-
-        // Open cursors of on-disk BTrees.
-        int numDiskComponents = includeMemComponent ? numBTrees - 1 : numBTrees;
-        ITreeIndexAccessor[] diskBTreeAccessors = new ITreeIndexAccessor[numDiskComponents];
-        int diskBTreeIx = 0;
-        while (btreesIter.hasNext()) {
-            BTree diskBTree = (BTree) ((LSMBTreeImmutableComponent) btreesIter.next()).getBTree();
-            diskBTreeAccessors[diskBTreeIx] = diskBTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            diskBTreeAccessors[diskBTreeIx].search(rangeCursors[cursorIx], searchPred);
-            cursorIx++;
-            diskBTreeIx++;
-        }
         initPriorityQueue();
         proceed = true;
     }
diff --git a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeUtils.java b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeUtils.java
index 507ec02..f43c8a6 100644
--- a/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeUtils.java
+++ b/hyracks/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeUtils.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.btree.util;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
 import edu.uci.ics.hyracks.api.io.FileReference;
@@ -43,7 +45,7 @@
 import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;
 
 public class LSMBTreeUtils {
-    public static LSMBTree createLSMTree(IVirtualBufferCache virtualBufferCache, FileReference file,
+    public static LSMBTree createLSMTree(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] cmpFactories, int[] bloomFilterKeyFields, double bloomFilterFalsePositiveRate,
             ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
@@ -73,7 +75,7 @@
 
         ILSMIndexFileManager fileNameManager = new LSMBTreeFileManager(diskFileMapProvider, file, diskBTreeFactory);
 
-        LSMBTree lsmTree = new LSMBTree(virtualBufferCache, interiorFrameFactory, insertLeafFrameFactory,
+        LSMBTree lsmTree = new LSMBTree(virtualBufferCaches, interiorFrameFactory, insertLeafFrameFactory,
                 deleteLeafFrameFactory, fileNameManager, diskBTreeFactory, bulkLoadBTreeFactory, bloomFilterFactory,
                 bloomFilterFalsePositiveRate, diskFileMapProvider, typeTraits.length, cmpFactories, mergePolicy,
                 opTracker, ioScheduler, ioOpCallbackProvider);
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMComponent.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMComponent.java
index 72a3e1f..1d1de53 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMComponent.java
@@ -18,7 +18,15 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMOperationType;
 
 public interface ILSMComponent {
-    public boolean threadEnter(LSMOperationType opType) throws InterruptedException;
+
+    enum LSMComponentType {
+        MEMORY,
+        DISK
+    }
+
+    public boolean threadEnter(LSMOperationType opType) throws InterruptedException, HyracksDataException;
 
     public void threadExit(LSMOperationType opType, boolean failedOperation) throws HyracksDataException;
+
+    public LSMComponentType getType();
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndex.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndex.java
index 105b53a..a92cb42 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndex.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndex.java
@@ -32,11 +32,11 @@
  * concurrent searches/updates/merges may be ongoing.
  */
 public interface ILSMIndex extends IIndex {
-    
+
     public void deactivate(boolean flushOnExit) throws HyracksDataException;
 
     public ILSMIndexAccessor createAccessor(IModificationOperationCallback modificationCallback,
-            ISearchOperationCallback searchCallback);
+            ISearchOperationCallback searchCallback) throws HyracksDataException;
 
     public boolean getFlushStatus();
 
@@ -45,4 +45,6 @@
     public ILSMIOOperationScheduler getIOScheduler();
 
     public List<ILSMComponent> getImmutableComponents();
+
+    public int getCurrentMutableComponentId();
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexInternal.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexInternal.java
index 8fb7bdd..41e1425 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexInternal.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexInternal.java
@@ -28,7 +28,7 @@
 
 public interface ILSMIndexInternal extends ILSMIndex {
     public ILSMIndexAccessorInternal createAccessor(IModificationOperationCallback modificationCallback,
-            ISearchOperationCallback searchCallback);
+            ISearchOperationCallback searchCallback) throws HyracksDataException;
 
     public void modify(IIndexOperationContext ictx, ITupleReference tuple) throws HyracksDataException, IndexException;
 
@@ -58,14 +58,6 @@
      */
     public void getOperationalComponents(ILSMIndexOperationContext ctx);
 
-    public List<ILSMComponent> getImmutableComponents();
-    
-    public ILSMComponent getMutableComponent();
-
     public void markAsValid(ILSMComponent lsmComponent) throws HyracksDataException;
 
-    public void setFlushStatus(boolean needsFlush);
-
-    public boolean isFull();
-
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
index bbd2ca8..fcd4037 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
@@ -26,4 +26,6 @@
     public ISearchOperationCallback getSearchOperationCallback();
 
     public IModificationOperationCallback getModificationCallback();
+
+    public void setCurrentMutableComponentId(int currentMutableComponentId);
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMOperationTracker.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMOperationTracker.java
index 2659b27..ccde3ba 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMOperationTracker.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMOperationTracker.java
@@ -36,7 +36,7 @@
      * then this method does not block and returns false.
      * Otherwise, this method returns true, and the operation is considered 'active' in the index.
      */
-    public void beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
+    public boolean beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
             IModificationOperationCallback modificationCallback) throws HyracksDataException;
 
     /**
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentAdderCallback.java
similarity index 80%
rename from hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java
rename to hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentAdderCallback.java
index ff4a5d0..ba37740 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentAdderCallback.java
@@ -12,12 +12,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.hyracks.storage.am.lsm.common.impls;
+package edu.uci.ics.hyracks.storage.am.lsm.common.api;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 
-public interface IMutableResetCallback {
+public interface IMutableComponentAdderCallback {
 
-    public void reset() throws HyracksDataException;
-
-}
+    public void addComponent() throws HyracksDataException;
+}
\ No newline at end of file
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentSwitcherCallback.java
similarity index 75%
copy from hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java
copy to hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentSwitcherCallback.java
index ff4a5d0..8eae3a4 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/IMutableResetCallback.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IMutableComponentSwitcherCallback.java
@@ -12,12 +12,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.hyracks.storage.am.lsm.common.impls;
+package edu.uci.ics.hyracks.storage.am.lsm.common.api;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 
-public interface IMutableResetCallback {
+public interface IMutableComponentSwitcherCallback {
 
-    public void reset() throws HyracksDataException;
+    public void switchComponents() throws HyracksDataException;
 
-}
+    public void setFlushStatus(boolean isFlushNeeded);
+}
\ No newline at end of file
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IVirtualBufferCacheProvider.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IVirtualBufferCacheProvider.java
index cd75df0..eff390f 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IVirtualBufferCacheProvider.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/IVirtualBufferCacheProvider.java
@@ -15,9 +15,10 @@
 package edu.uci.ics.hyracks.storage.am.lsm.common.api;
 
 import java.io.Serializable;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 
 public interface IVirtualBufferCacheProvider extends Serializable {
-    public IVirtualBufferCache getVirtualBufferCache(IHyracksTaskContext ctx);
+    public List<IVirtualBufferCache> getVirtualBufferCaches(IHyracksTaskContext ctx);
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/dataflow/AbstractLSMIndexDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/dataflow/AbstractLSMIndexDataflowHelper.java
index e79a394..b1bf6b4 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/dataflow/AbstractLSMIndexDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/dataflow/AbstractLSMIndexDataflowHelper.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.common.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.storage.am.common.dataflow.IIndexOperatorDescriptor;
 import edu.uci.ics.hyracks.storage.am.common.dataflow.IndexDataflowHelper;
@@ -30,26 +32,26 @@
 
     protected final double bloomFilterFalsePositiveRate;
 
-    protected final IVirtualBufferCache virtualBufferCache;
+    protected final List<IVirtualBufferCache> virtualBufferCaches;
     protected final ILSMMergePolicy mergePolicy;
     protected final ILSMIOOperationScheduler ioScheduler;
     protected final ILSMOperationTrackerProvider opTrackerFactory;
     protected final ILSMIOOperationCallbackProvider ioOpCallbackProvider;
 
     public AbstractLSMIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, ILSMMergePolicy mergePolicy,
+            List<IVirtualBufferCache> virtualBufferCaches, ILSMMergePolicy mergePolicy,
             ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        this(opDesc, ctx, partition, virtualBufferCache, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
+        this(opDesc, ctx, partition, virtualBufferCaches, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
                 opTrackerFactory, ioScheduler, ioOpCallbackProvider);
     }
 
     public AbstractLSMIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy,
-            ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
-            ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
+            List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate,
+            ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
+            ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
         super(opDesc, ctx, partition);
-        this.virtualBufferCache = virtualBufferCache;
+        this.virtualBufferCaches = virtualBufferCaches;
         this.bloomFilterFalsePositiveRate = bloomFilterFalsePositiveRate;
         this.mergePolicy = mergePolicy;
         this.opTrackerFactory = opTrackerFactory;
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractImmutableLSMComponent.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractImmutableLSMComponent.java
index 376c2e4..59132e6 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractImmutableLSMComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractImmutableLSMComponent.java
@@ -80,6 +80,11 @@
         }
     }
 
+    @Override
+    public LSMComponentType getType() {
+        return LSMComponentType.DISK;
+    }
+
     protected abstract void destroy() throws HyracksDataException;
 
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
index d9da9e5..86f299f 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
@@ -18,6 +18,8 @@
 import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
@@ -44,7 +46,8 @@
     protected final ILSMIOOperationCallbackProvider ioOpCallbackProvider;
 
     // In-memory components.   
-    protected final IVirtualBufferCache virtualBufferCache;
+    protected final List<IVirtualBufferCache> virtualBufferCaches;
+    protected AtomicInteger currentMutableComponentId;
 
     // On-disk components.    
     protected final IBufferCache diskBufferCache;
@@ -55,13 +58,13 @@
 
     protected boolean isActivated;
 
-    private boolean needsFlush = false;
+    protected final AtomicBoolean[] needsFlush;
 
-    public AbstractLSMIndex(IVirtualBufferCache virtualBufferCache, IBufferCache diskBufferCache,
+    public AbstractLSMIndex(List<IVirtualBufferCache> virtualBufferCaches, IBufferCache diskBufferCache,
             ILSMIndexFileManager fileManager, IFileMapProvider diskFileMapProvider,
             double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        this.virtualBufferCache = virtualBufferCache;
+        this.virtualBufferCaches = virtualBufferCaches;
         this.diskBufferCache = diskBufferCache;
         this.diskFileMapProvider = diskFileMapProvider;
         this.fileManager = fileManager;
@@ -72,6 +75,11 @@
         isActivated = false;
         componentsRef = new AtomicReference<List<ILSMComponent>>();
         componentsRef.set(new LinkedList<ILSMComponent>());
+        currentMutableComponentId = new AtomicInteger();
+        needsFlush = new AtomicBoolean[virtualBufferCaches.size()];
+        for (int i = 0; i < virtualBufferCaches.size(); i++) {
+            needsFlush[i] = new AtomicBoolean();
+        }
     }
 
     protected void forceFlushDirtyPages(ITreeIndex treeIndex) throws HyracksDataException {
@@ -160,13 +168,8 @@
     }
 
     @Override
-    public void setFlushStatus(boolean needsFlush) {
-        this.needsFlush = needsFlush;
-    }
-
-    @Override
     public boolean getFlushStatus() {
-        return needsFlush;
+        return needsFlush[currentMutableComponentId.get()].get();
     }
 
     @Override
@@ -180,13 +183,13 @@
     }
 
     @Override
-    public boolean isFull() {
-        return virtualBufferCache.isFull();
+    public IBufferCache getBufferCache() {
+        return diskBufferCache;
     }
 
     @Override
-    public IBufferCache getBufferCache() {
-        return diskBufferCache;
+    public int getCurrentMutableComponentId() {
+        return currentMutableComponentId.get();
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractMutableLSMComponent.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractMutableLSMComponent.java
index 43501f9..05b0a4f 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractMutableLSMComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/AbstractMutableLSMComponent.java
@@ -18,6 +18,8 @@
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentAdderCallback;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentSwitcherCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 
 public abstract class AbstractMutableLSMComponent implements ILSMComponent {
@@ -25,36 +27,52 @@
     private int readerCount;
     private int writerCount;
     private ComponentState state;
-    private IMutableResetCallback resetCallback;
     private final IVirtualBufferCache vbc;
 
+    private IMutableComponentAdderCallback adderCallback;
+    private IMutableComponentSwitcherCallback switcherCallback;
+
     private final AtomicBoolean isModified;
+    private boolean requestedToBeActive;
 
     private enum ComponentState {
         READABLE_WRITABLE,
         READABLE_UNWRITABLE,
         READABLE_UNWRITABLE_FLUSHING,
-        UNREADABLE_UNWRITABLE
+        UNREADABLE_UNWRITABLE,
+        INACTIVE_READABLE_WRITABLE
     }
 
-    public AbstractMutableLSMComponent(IVirtualBufferCache vbc) {
+    public AbstractMutableLSMComponent(IVirtualBufferCache vbc, boolean isActive) {
         this.vbc = vbc;
         readerCount = 0;
         writerCount = 0;
-        state = ComponentState.READABLE_WRITABLE;
+        if (isActive) {
+            state = ComponentState.READABLE_WRITABLE;
+        } else {
+            state = ComponentState.INACTIVE_READABLE_WRITABLE;
+        }
         isModified = new AtomicBoolean();
     }
 
     @Override
-    public synchronized boolean threadEnter(LSMOperationType opType) throws InterruptedException {
+    public synchronized boolean threadEnter(LSMOperationType opType) throws InterruptedException, HyracksDataException {
         switch (opType) {
             case FORCE_MODIFICATION:
+                if (state == ComponentState.INACTIVE_READABLE_WRITABLE && requestedToBeActive) {
+                    state = ComponentState.READABLE_WRITABLE;
+                    requestedToBeActive = false;
+                }
                 if (state != ComponentState.READABLE_WRITABLE && state != ComponentState.READABLE_UNWRITABLE) {
                     return false;
                 }
                 writerCount++;
                 break;
             case MODIFICATION:
+                if (state == ComponentState.INACTIVE_READABLE_WRITABLE && requestedToBeActive) {
+                    state = ComponentState.READABLE_WRITABLE;
+                    requestedToBeActive = false;
+                }
                 if (state != ComponentState.READABLE_WRITABLE) {
                     return false;
                 }
@@ -73,9 +91,11 @@
                 }
 
                 state = ComponentState.READABLE_UNWRITABLE_FLUSHING;
+                switcherCallback.setFlushStatus(false);
                 while (writerCount > 0) {
                     wait();
                 }
+                switcherCallback.switchComponents();
                 readerCount++;
                 break;
             default:
@@ -92,27 +112,36 @@
                 writerCount--;
                 if (state == ComponentState.READABLE_WRITABLE && isFull()) {
                     state = ComponentState.READABLE_UNWRITABLE;
+                    switcherCallback.setFlushStatus(true);
                 }
                 break;
             case SEARCH:
                 readerCount--;
                 if (state == ComponentState.UNREADABLE_UNWRITABLE && readerCount == 0) {
                     reset();
-                    resetCallback.reset();
-                    state = ComponentState.READABLE_WRITABLE;
+                    adderCallback.addComponent();
+                    if (requestedToBeActive == true) {
+                        state = ComponentState.READABLE_WRITABLE;
+                        requestedToBeActive = false;
+                    } else {
+                        state = ComponentState.INACTIVE_READABLE_WRITABLE;
+                    }
                 } else if (state == ComponentState.READABLE_WRITABLE && isFull()) {
                     state = ComponentState.READABLE_UNWRITABLE;
+                    switcherCallback.setFlushStatus(true);
                 }
                 break;
             case FLUSH:
-                if (failedOperation) {
-                    state = isFull() ? ComponentState.READABLE_UNWRITABLE : ComponentState.READABLE_WRITABLE;
-                }
                 readerCount--;
                 if (readerCount == 0) {
                     reset();
-                    resetCallback.reset();
-                    state = ComponentState.READABLE_WRITABLE;
+                    adderCallback.addComponent();
+                    if (requestedToBeActive == true) {
+                        state = ComponentState.READABLE_WRITABLE;
+                        requestedToBeActive = false;
+                    } else {
+                        state = ComponentState.INACTIVE_READABLE_WRITABLE;
+                    }
                 } else if (state == ComponentState.READABLE_UNWRITABLE_FLUSHING) {
                     state = ComponentState.UNREADABLE_UNWRITABLE;
                 }
@@ -123,8 +152,28 @@
         notifyAll();
     }
 
-    public void registerOnResetCallback(IMutableResetCallback resetCallback) {
-        this.resetCallback = resetCallback;
+    @Override
+    public LSMComponentType getType() {
+        return LSMComponentType.MEMORY;
+    }
+
+    public synchronized boolean isReadable() {
+        if (state == ComponentState.UNREADABLE_UNWRITABLE || state == ComponentState.INACTIVE_READABLE_WRITABLE) {
+            return false;
+        }
+        return true;
+    }
+
+    public synchronized void setActive() {
+        requestedToBeActive = true;
+    }
+
+    public void registerOnResetCallback(IMutableComponentAdderCallback adderCallback) {
+        this.adderCallback = adderCallback;
+    }
+
+    public void registerOnFlushCallback(IMutableComponentSwitcherCallback switcherCallback) {
+        this.switcherCallback = switcherCallback;
     }
 
     public void setIsModified() {
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMHarness.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMHarness.java
index d30866e..364bc47 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMHarness.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMHarness.java
@@ -34,6 +34,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentAdderCallback;
 
 public class LSMHarness implements ILSMHarness {
     private static final Logger LOGGER = Logger.getLogger(LSMHarness.class.getName());
@@ -49,9 +50,6 @@
     }
 
     private void threadExit(ILSMIndexOperationContext opCtx, LSMOperationType opType) throws HyracksDataException {
-        if (!lsmIndex.getFlushStatus() && lsmIndex.isFull()) {
-            lsmIndex.setFlushStatus(true);
-        }
         opTracker.afterOperation(lsmIndex, opType, opCtx.getSearchOperationCallback(), opCtx.getModificationCallback());
     }
 
@@ -64,14 +62,22 @@
             lsmIndex.getOperationalComponents(ctx);
             List<ILSMComponent> components = ctx.getComponentHolder();
             try {
-
-                for (ILSMComponent c : components) {
-                    if (!c.threadEnter(opType)) {
-                        break;
+                // The purpose of the synchronized block is to make the beforeOperation call and entering the mutable component an atomic operation.
+                synchronized (this) {
+                    for (ILSMComponent c : components) {
+                        if (!c.threadEnter(opType)) {
+                            break;
+                        }
+                        numEntered++;
                     }
-                    numEntered++;
+                    entranceSuccessful = numEntered == components.size();
+                    if (entranceSuccessful) {
+                        if (!opTracker.beforeOperation(lsmIndex, opType, ctx.getSearchOperationCallback(),
+                                ctx.getModificationCallback())) {
+                            entranceSuccessful = false;
+                        }
+                    }
                 }
-                entranceSuccessful = numEntered == components.size();
             } catch (InterruptedException e) {
                 entranceSuccessful = false;
                 throw new HyracksDataException(e);
@@ -90,7 +96,6 @@
                 return false;
             }
         }
-        opTracker.beforeOperation(lsmIndex, opType, ctx.getSearchOperationCallback(), ctx.getModificationCallback());
         return true;
     }
 
@@ -163,14 +168,15 @@
             return;
         }
 
-        lsmIndex.setFlushStatus(false);
-
         if (!lsmIndex.scheduleFlush(ctx, callback)) {
             callback.beforeOperation();
             callback.afterOperation(null, null);
-            AbstractMutableLSMComponent mutableComponent = (AbstractMutableLSMComponent) lsmIndex.getMutableComponent();
-            mutableComponent.registerOnResetCallback(new IMutableResetCallback() {
-                public void reset() throws HyracksDataException {
+            AbstractMutableLSMComponent mutableComponent = (AbstractMutableLSMComponent) ctx.getComponentHolder()
+                    .get(0);
+            mutableComponent.registerOnResetCallback(new IMutableComponentAdderCallback() {
+
+                @Override
+                public void addComponent() throws HyracksDataException {
                     // do nothing
                 }
             });
@@ -191,9 +197,11 @@
         operation.getCallback().afterOperation(null, newComponent);
         lsmIndex.markAsValid(newComponent);
 
-        AbstractMutableLSMComponent mutableComponent = (AbstractMutableLSMComponent) lsmIndex.getMutableComponent();
-        mutableComponent.registerOnResetCallback(new IMutableResetCallback() {
-            public void reset() throws HyracksDataException {
+        AbstractMutableLSMComponent flushingComponent = (AbstractMutableLSMComponent) ctx.getComponentHolder().get(0);
+        flushingComponent.registerOnResetCallback(new IMutableComponentAdderCallback() {
+
+            @Override
+            public void addComponent() throws HyracksDataException {
                 lsmIndex.addComponent(newComponent);
                 int numComponents = lsmIndex.getImmutableComponents().size();
                 try {
@@ -201,7 +209,6 @@
                 } catch (IndexException e) {
                     throw new HyracksDataException(e);
                 }
-
             }
         });
 
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMIndexSearchCursor.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMIndexSearchCursor.java
index b6ca21b..ea23091 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMIndexSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMIndexSearchCursor.java
@@ -39,7 +39,7 @@
     protected PriorityQueueComparator pqCmp;
     protected MultiComparator cmp;
     protected boolean needPush;
-    protected boolean includeMemComponent;
+    protected boolean includeMutableComponent;
     protected ILSMHarness lsmHarness;
     protected final ILSMIndexOperationContext opCtx;
 
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMOperationType.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMOperationType.java
index d932e6d..853b6d0 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMOperationType.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMOperationType.java
@@ -19,6 +19,5 @@
     MODIFICATION,
     FORCE_MODIFICATION,
     FLUSH,
-    MERGE,
-    NOOP
+    MERGE
 }
diff --git a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
index 19ee4b8..752e923 100644
--- a/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
+++ b/hyracks/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
@@ -32,11 +32,12 @@
     }
 
     @Override
-    public void beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
+    public boolean beforeOperation(ILSMIndex index, LSMOperationType opType, ISearchOperationCallback searchCallback,
             IModificationOperationCallback modificationCallback) throws HyracksDataException {
         if (opType == LSMOperationType.MODIFICATION) {
             threadRefCount.incrementAndGet();
         }
+        return true;
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelper.java
index 1afd9d5..ee8febe 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelper.java
@@ -14,6 +14,8 @@
  */
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndex;
@@ -34,18 +36,18 @@
 public final class LSMInvertedIndexDataflowHelper extends AbstractLSMIndexDataflowHelper {
 
     public LSMInvertedIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, ILSMMergePolicy mergePolicy,
+            List<IVirtualBufferCache> virtualBufferCaches, ILSMMergePolicy mergePolicy,
             ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        this(opDesc, ctx, partition, virtualBufferCache, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
+        this(opDesc, ctx, partition, virtualBufferCaches, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
                 opTrackerFactory, ioScheduler, ioOpCallbackProvider);
     }
 
     public LSMInvertedIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy,
-            ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
-            ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(opDesc, ctx, partition, virtualBufferCache, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
+            List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate,
+            ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
+            ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
+        super(opDesc, ctx, partition, virtualBufferCaches, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
                 ioScheduler, ioOpCallbackProvider);
     }
 
@@ -55,7 +57,7 @@
         try {
             IBufferCache diskBufferCache = opDesc.getStorageManager().getBufferCache(ctx);
             IFileMapProvider diskFileMapProvider = opDesc.getStorageManager().getFileMapProvider(ctx);
-            LSMInvertedIndex invIndex = InvertedIndexUtils.createLSMInvertedIndex(virtualBufferCache,
+            LSMInvertedIndex invIndex = InvertedIndexUtils.createLSMInvertedIndex(virtualBufferCaches,
                     diskFileMapProvider, invIndexOpDesc.getInvListsTypeTraits(),
                     invIndexOpDesc.getInvListsComparatorFactories(), invIndexOpDesc.getTokenTypeTraits(),
                     invIndexOpDesc.getTokenComparatorFactories(), invIndexOpDesc.getTokenizerFactory(),
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelperFactory.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelperFactory.java
index c9f81fc..85aa312 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelperFactory.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/LSMInvertedIndexDataflowHelperFactory.java
@@ -41,7 +41,7 @@
     public IndexDataflowHelper createIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
             int partition) {
         return new LSMInvertedIndexDataflowHelper(opDesc, ctx, partition,
-                virtualBufferCacheProvider.getVirtualBufferCache(ctx), bloomFilterFalsePositiveRate,
+                virtualBufferCacheProvider.getVirtualBufferCaches(ctx), bloomFilterFalsePositiveRate,
                 mergePolicyProvider.getMergePolicy(ctx), opTrackerFactory, ioSchedulerProvider.getIOScheduler(ctx),
                 ioOpCallbackProvider);
     }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelper.java
index 0dbd06b..1acb437 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelper.java
@@ -14,6 +14,8 @@
  */
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndex;
@@ -34,7 +36,7 @@
 public final class PartitionedLSMInvertedIndexDataflowHelper extends AbstractLSMIndexDataflowHelper {
 
     public PartitionedLSMInvertedIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
-            int partition, IVirtualBufferCache virtualBufferCache, ILSMMergePolicy mergePolicy,
+            int partition, List<IVirtualBufferCache> virtualBufferCache, ILSMMergePolicy mergePolicy,
             ILSMOperationTrackerProvider opTrackerFactory, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
         this(opDesc, ctx, partition, virtualBufferCache, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE, mergePolicy,
@@ -42,10 +44,10 @@
     }
 
     public PartitionedLSMInvertedIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
-            int partition, IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate,
+            int partition, List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(opDesc, ctx, partition, virtualBufferCache, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
+        super(opDesc, ctx, partition, virtualBufferCaches, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
                 ioScheduler, ioOpCallbackProvider);
     }
 
@@ -56,7 +58,7 @@
             IBufferCache diskBufferCache = opDesc.getStorageManager().getBufferCache(ctx);
             IFileMapProvider diskFileMapProvider = opDesc.getStorageManager().getFileMapProvider(ctx);
             PartitionedLSMInvertedIndex invIndex = InvertedIndexUtils.createPartitionedLSMInvertedIndex(
-                    virtualBufferCache, diskFileMapProvider, invIndexOpDesc.getInvListsTypeTraits(),
+                    virtualBufferCaches, diskFileMapProvider, invIndexOpDesc.getInvListsTypeTraits(),
                     invIndexOpDesc.getInvListsComparatorFactories(), invIndexOpDesc.getTokenTypeTraits(),
                     invIndexOpDesc.getTokenComparatorFactories(), invIndexOpDesc.getTokenizerFactory(),
                     diskBufferCache, file.getFile().getPath(), bloomFilterFalsePositiveRate, mergePolicy,
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelperFactory.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelperFactory.java
index 67cab6d..63d99aa 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelperFactory.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/dataflow/PartitionedLSMInvertedIndexDataflowHelperFactory.java
@@ -41,7 +41,7 @@
     public IndexDataflowHelper createIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
             int partition) {
         return new PartitionedLSMInvertedIndexDataflowHelper(opDesc, ctx, partition,
-                virtualBufferCacheProvider.getVirtualBufferCache(ctx), bloomFilterFalsePositiveRate,
+                virtualBufferCacheProvider.getVirtualBufferCaches(ctx), bloomFilterFalsePositiveRate,
                 mergePolicyProvider.getMergePolicy(ctx), opTrackerFactory, ioSchedulerProvider.getIOScheduler(ctx),
                 ioOpCallbackProvider);
     }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
index 98df518..5b11f66 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
@@ -42,12 +42,13 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.IVirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexDuplicateKeyException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
 import edu.uci.ics.hyracks.storage.am.common.tuples.PermutingTupleReference;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent.LSMComponentType;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponentFactory;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
@@ -59,9 +60,11 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentSwitcherCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.freepage.VirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractLSMIndex;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractMutableLSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.BTreeFactory;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.BlockingIOOperationCallbackWrapper;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
@@ -80,8 +83,7 @@
 public class LSMInvertedIndex extends AbstractLSMIndex implements IInvertedIndex {
 
     // In-memory components.
-    protected final LSMInvertedIndexMutableComponent mutableComponent;
-    protected final IVirtualFreePageManager virtualFreePageManager;
+    private final List<LSMInvertedIndexMutableComponent> mutableComponents;
     protected final IBinaryTokenizerFactory tokenizerFactory;
 
     // On-disk components.
@@ -94,31 +96,56 @@
     protected final ITypeTraits[] tokenTypeTraits;
     protected final IBinaryComparatorFactory[] tokenCmpFactories;
 
-    public LSMInvertedIndex(IVirtualBufferCache virtualBufferCache, OnDiskInvertedIndexFactory diskInvIndexFactory,
-            BTreeFactory deletedKeysBTreeFactory, BloomFilterFactory bloomFilterFactory,
-            double bloomFilterFalsePositiveRate, ILSMIndexFileManager fileManager,
-            IFileMapProvider diskFileMapProvider, ITypeTraits[] invListTypeTraits,
+    public LSMInvertedIndex(List<IVirtualBufferCache> virtualBufferCaches,
+            OnDiskInvertedIndexFactory diskInvIndexFactory, BTreeFactory deletedKeysBTreeFactory,
+            BloomFilterFactory bloomFilterFactory, double bloomFilterFalsePositiveRate,
+            ILSMIndexFileManager fileManager, IFileMapProvider diskFileMapProvider, ITypeTraits[] invListTypeTraits,
             IBinaryComparatorFactory[] invListCmpFactories, ITypeTraits[] tokenTypeTraits,
             IBinaryComparatorFactory[] tokenCmpFactories, IBinaryTokenizerFactory tokenizerFactory,
             ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) throws IndexException {
-        super(virtualBufferCache, diskInvIndexFactory.getBufferCache(), fileManager, diskFileMapProvider,
+        super(virtualBufferCaches, diskInvIndexFactory.getBufferCache(), fileManager, diskFileMapProvider,
                 bloomFilterFalsePositiveRate, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider);
-        this.virtualFreePageManager = new VirtualFreePageManager(virtualBufferCache.getNumPages());
+
         this.tokenizerFactory = tokenizerFactory;
         this.invListTypeTraits = invListTypeTraits;
         this.invListCmpFactories = invListCmpFactories;
         this.tokenTypeTraits = tokenTypeTraits;
         this.tokenCmpFactories = tokenCmpFactories;
-        // Create in-memory component.
-        InMemoryInvertedIndex memInvIndex = createInMemoryInvertedIndex(virtualBufferCache);
-        BTree deleteKeysBTree = BTreeUtils.createBTree(virtualBufferCache, new VirtualFreePageManager(
-                virtualBufferCache.getNumPages()), ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(),
-                invListTypeTraits, invListCmpFactories, BTreeLeafFrameType.REGULAR_NSM, new FileReference(new File(
-                        fileManager.getBaseDir() + "_virtual_del")));
-        mutableComponent = new LSMInvertedIndexMutableComponent(memInvIndex, deleteKeysBTree, virtualBufferCache);
+
         componentFactory = new LSMInvertedIndexComponentFactory(diskInvIndexFactory, deletedKeysBTreeFactory,
                 bloomFilterFactory);
+
+        mutableComponents = new ArrayList<LSMInvertedIndexMutableComponent>();
+        final int numMutableComponents = virtualBufferCaches.size();
+        int i = 0;
+        for (IVirtualBufferCache virtualBufferCache : virtualBufferCaches) {
+            InMemoryInvertedIndex memInvIndex = createInMemoryInvertedIndex(virtualBufferCache,
+                    new VirtualFreePageManager(virtualBufferCache.getNumPages()), i);
+            BTree deleteKeysBTree = BTreeUtils.createBTree(virtualBufferCache, new VirtualFreePageManager(
+                    virtualBufferCache.getNumPages()), ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(),
+                    invListTypeTraits, invListCmpFactories, BTreeLeafFrameType.REGULAR_NSM, new FileReference(new File(
+                            fileManager.getBaseDir() + "_virtual_del_" + i)));
+            LSMInvertedIndexMutableComponent mutableComponent = new LSMInvertedIndexMutableComponent(memInvIndex,
+                    deleteKeysBTree, virtualBufferCache, i == 0 ? true : false);
+
+            mutableComponent.registerOnFlushCallback(new IMutableComponentSwitcherCallback() {
+
+                @Override
+                public void switchComponents() throws HyracksDataException {
+                    currentMutableComponentId.set((currentMutableComponentId.get() + 1) % numMutableComponents);
+                    mutableComponents.get(currentMutableComponentId.get()).setActive();
+                }
+
+                @Override
+                public void setFlushStatus(boolean isFlushNeeded) {
+                    needsFlush[currentMutableComponentId.get()].set(isFlushNeeded);
+                }
+            });
+
+            mutableComponents.add(mutableComponent);
+            ++i;
+        }
     }
 
     @Override
@@ -140,11 +167,14 @@
 
         try {
             List<ILSMComponent> immutableComponents = componentsRef.get();
-            ((IVirtualBufferCache) mutableComponent.getInvIndex().getBufferCache()).open();
-            mutableComponent.getInvIndex().create();
-            mutableComponent.getInvIndex().activate();
-            mutableComponent.getDeletedKeysBTree().create();
-            mutableComponent.getDeletedKeysBTree().activate();
+            for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+                ((IVirtualBufferCache) mutableComponent.getInvIndex().getBufferCache()).open();
+                mutableComponent.getInvIndex().create();
+                mutableComponent.getInvIndex().activate();
+                mutableComponent.getDeletedKeysBTree().create();
+                mutableComponent.getDeletedKeysBTree().activate();
+            }
+
             immutableComponents.clear();
             List<LSMComponentFileReferences> validFileReferences = fileManager.cleanupAndGetValidFiles();
             for (LSMComponentFileReferences lsmComonentFileReference : validFileReferences) {
@@ -172,9 +202,11 @@
             throw new HyracksDataException("Failed to clear the index since it is not activated.");
         }
         List<ILSMComponent> immutableComponents = componentsRef.get();
-        mutableComponent.getInvIndex().clear();
-        mutableComponent.getDeletedKeysBTree().clear();
-        mutableComponent.reset();
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getInvIndex().clear();
+            mutableComponent.getDeletedKeysBTree().clear();
+            mutableComponent.reset();
+        }
         for (ILSMComponent c : immutableComponents) {
             LSMInvertedIndexImmutableComponent component = (LSMInvertedIndexImmutableComponent) c;
             component.getBloomFilter().deactivate();
@@ -214,11 +246,13 @@
             component.getInvIndex().deactivate();
             component.getDeletedKeysBTree().deactivate();
         }
-        mutableComponent.getInvIndex().deactivate();
-        mutableComponent.getDeletedKeysBTree().deactivate();
-        mutableComponent.getInvIndex().destroy();
-        mutableComponent.getDeletedKeysBTree().destroy();
-        ((IVirtualBufferCache) mutableComponent.getInvIndex().getBufferCache()).close();
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getInvIndex().deactivate();
+            mutableComponent.getDeletedKeysBTree().deactivate();
+            mutableComponent.getInvIndex().destroy();
+            mutableComponent.getDeletedKeysBTree().destroy();
+            ((IVirtualBufferCache) mutableComponent.getInvIndex().getBufferCache()).close();
+        }
     }
 
     @Override
@@ -232,8 +266,10 @@
             throw new HyracksDataException("Failed to destroy the index since it is activated.");
         }
 
-        mutableComponent.getInvIndex().destroy();
-        mutableComponent.getDeletedKeysBTree().destroy();
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getInvIndex().destroy();
+            mutableComponent.getDeletedKeysBTree().destroy();
+        }
         List<ILSMComponent> immutableComponents = componentsRef.get();
         for (ILSMComponent c : immutableComponents) {
             LSMInvertedIndexImmutableComponent component = (LSMInvertedIndexImmutableComponent) c;
@@ -245,23 +281,30 @@
     }
 
     @Override
-    public ILSMComponent getMutableComponent() {
-        return mutableComponent;
-    }
-    
-    @Override
     public void getOperationalComponents(ILSMIndexOperationContext ctx) {
         List<ILSMComponent> immutableComponents = componentsRef.get();
         List<ILSMComponent> operationalComponents = ctx.getComponentHolder();
         operationalComponents.clear();
+        int cmc = currentMutableComponentId.get();
+        ctx.setCurrentMutableComponentId(cmc);
+        int numMutableComponents = mutableComponents.size();
         switch (ctx.getOperation()) {
             case FLUSH:
             case DELETE:
             case INSERT:
-                operationalComponents.add(mutableComponent);
+                operationalComponents.add(mutableComponents.get(cmc));
                 break;
             case SEARCH:
-                operationalComponents.add(mutableComponent);
+                for (int i = 0; i < numMutableComponents - 1; i++) {
+                    LSMInvertedIndexMutableComponent mutableComponent = mutableComponents.get((cmc + i + 1)
+                            % numMutableComponents);
+                    if (mutableComponent.isReadable()) {
+                        // Make sure newest components are added first
+                        operationalComponents.add(0, mutableComponent);
+                    }
+                }
+                // The current mutable component is always added
+                operationalComponents.add(0, mutableComponents.get(cmc));
                 operationalComponents.addAll(immutableComponents);
                 break;
             case MERGE:
@@ -300,17 +343,17 @@
         switch (ctx.getOperation()) {
             case INSERT: {
                 // Insert into the in-memory inverted index.                
-                ctx.memInvIndexAccessor.insert(tuple);
+                ctx.currentMutableInvIndexAccessors.insert(tuple);
                 break;
             }
             case DELETE: {
                 // First remove all entries in the in-memory inverted index (if any).
-                ctx.memInvIndexAccessor.delete(tuple);
+                ctx.currentMutableInvIndexAccessors.delete(tuple);
                 // Insert key into the deleted-keys BTree.
                 ctx.keysOnlyTuple.reset(tuple);
                 try {
-                    ctx.deletedKeysBTreeAccessor.insert(ctx.keysOnlyTuple);
-                } catch (TreeIndexDuplicateKeyException e) {
+                    ctx.currentDeletedKeysBTreeAccessors.insert(ctx.keysOnlyTuple);
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Key has already been deleted.
                 }
                 break;
@@ -319,7 +362,7 @@
                 throw new UnsupportedOperationException("Operation " + ctx.getOperation() + " not supported.");
             }
         }
-        mutableComponent.setIsModified();
+        mutableComponents.get(currentMutableComponentId.get()).setIsModified();
     }
 
     @Override
@@ -328,59 +371,59 @@
         List<ILSMComponent> operationalComponents = ictx.getComponentHolder();
         int numComponents = operationalComponents.size();
         assert numComponents > 0;
-        boolean includeMutableComponent = operationalComponents.get(0) == mutableComponent;
+        boolean includeMutableComponent = false;
         ArrayList<IIndexAccessor> indexAccessors = new ArrayList<IIndexAccessor>(numComponents);
         ArrayList<IIndexAccessor> deletedKeysBTreeAccessors = new ArrayList<IIndexAccessor>(numComponents);
-        if (includeMutableComponent) {
-            IIndexAccessor invIndexAccessor = mutableComponent.getInvIndex().createAccessor(
-                    NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            indexAccessors.add(invIndexAccessor);
-            IIndexAccessor deletedKeysAccessor = mutableComponent.getDeletedKeysBTree().createAccessor(
-                    NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            deletedKeysBTreeAccessors.add(deletedKeysAccessor);
-        }
 
-        for (int i = includeMutableComponent ? 1 : 0; i < operationalComponents.size(); i++) {
-            LSMInvertedIndexImmutableComponent component = (LSMInvertedIndexImmutableComponent) operationalComponents
-                    .get(i);
-            IIndexAccessor invIndexAccessor = component.getInvIndex().createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            indexAccessors.add(invIndexAccessor);
-            IIndexAccessor deletedKeysAccessor = component.getDeletedKeysBTree().createAccessor(
-                    NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            deletedKeysBTreeAccessors.add(deletedKeysAccessor);
+        for (int i = 0; i < operationalComponents.size(); i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            if (component.getType() == LSMComponentType.MEMORY) {
+                includeMutableComponent = true;
+                IIndexAccessor invIndexAccessor = ((LSMInvertedIndexMutableComponent) component).getInvIndex()
+                        .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                indexAccessors.add(invIndexAccessor);
+                IIndexAccessor deletedKeysAccessor = ((LSMInvertedIndexMutableComponent) component)
+                        .getDeletedKeysBTree().createAccessor(NoOpOperationCallback.INSTANCE,
+                                NoOpOperationCallback.INSTANCE);
+                deletedKeysBTreeAccessors.add(deletedKeysAccessor);
+            } else {
+                IIndexAccessor invIndexAccessor = ((LSMInvertedIndexImmutableComponent) component).getInvIndex()
+                        .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                indexAccessors.add(invIndexAccessor);
+                IIndexAccessor deletedKeysAccessor = ((LSMInvertedIndexImmutableComponent) component)
+                        .getDeletedKeysBTree().createAccessor(NoOpOperationCallback.INSTANCE,
+                                NoOpOperationCallback.INSTANCE);
+                deletedKeysBTreeAccessors.add(deletedKeysAccessor);
+            }
         }
 
         ICursorInitialState initState = createCursorInitialState(pred, ictx, includeMutableComponent, indexAccessors,
-                deletedKeysBTreeAccessors);
+                deletedKeysBTreeAccessors, operationalComponents);
         cursor.open(initState, pred);
     }
 
     private ICursorInitialState createCursorInitialState(ISearchPredicate pred, IIndexOperationContext ictx,
             boolean includeMutableComponent, ArrayList<IIndexAccessor> indexAccessors,
-            ArrayList<IIndexAccessor> deletedKeysBTreeAccessors) {
-        List<ILSMComponent> immutableComponents = componentsRef.get();
+            ArrayList<IIndexAccessor> deletedKeysBTreeAccessors, List<ILSMComponent> operationalComponents) {
         ICursorInitialState initState = null;
         PermutingTupleReference keysOnlyTuple = createKeysOnlyTupleReference();
         MultiComparator keyCmp = MultiComparator.createIgnoreFieldLength(invListCmpFactories);
-        List<ILSMComponent> operationalComponents = new ArrayList<ILSMComponent>();
-        if (includeMutableComponent) {
-            operationalComponents.add(mutableComponent);
-        }
-        operationalComponents.addAll(immutableComponents);
 
         // TODO: This check is not pretty, but it does the job. Come up with something more OO in the future.
         // Distinguish between regular searches and range searches (mostly used in merges).
         if (pred instanceof InvertedIndexSearchPredicate) {
             initState = new LSMInvertedIndexSearchCursorInitialState(keyCmp, keysOnlyTuple, indexAccessors,
-                    deletedKeysBTreeAccessors, mutableComponent.getDeletedKeysBTree().getLeafFrameFactory(), ictx,
-                    includeMutableComponent, lsmHarness, operationalComponents);
+                    deletedKeysBTreeAccessors, mutableComponents.get(currentMutableComponentId.get())
+                            .getDeletedKeysBTree().getLeafFrameFactory(), ictx, includeMutableComponent, lsmHarness,
+                    operationalComponents);
         } else {
-            InMemoryInvertedIndex memInvIndex = (InMemoryInvertedIndex) mutableComponent.getInvIndex();
+            InMemoryInvertedIndex memInvIndex = (InMemoryInvertedIndex) mutableComponents.get(
+                    currentMutableComponentId.get()).getInvIndex();
             MultiComparator tokensAndKeysCmp = MultiComparator.create(memInvIndex.getBTree().getComparatorFactories());
             initState = new LSMInvertedIndexRangeSearchCursorInitialState(tokensAndKeysCmp, keyCmp, keysOnlyTuple,
-                    mutableComponent.getDeletedKeysBTree().getLeafFrameFactory(), includeMutableComponent, lsmHarness,
-                    indexAccessors, deletedKeysBTreeAccessors, pred, operationalComponents);
+                    mutableComponents.get(currentMutableComponentId.get()).getDeletedKeysBTree().getLeafFrameFactory(),
+                    includeMutableComponent, lsmHarness, indexAccessors, deletedKeysBTreeAccessors, pred,
+                    operationalComponents);
         }
         return initState;
     }
@@ -401,19 +444,19 @@
     @Override
     public boolean scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        if (!mutableComponent.isModified()) {
+        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
+        if (!((AbstractMutableLSMComponent) flushingComponent).isModified()) {
             return false;
         }
         LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
         LSMInvertedIndexOpContext opCtx = createOpContext(NoOpOperationCallback.INSTANCE,
                 NoOpOperationCallback.INSTANCE);
-        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
         opCtx.setOperation(IndexOperation.FLUSH);
         opCtx.getComponentHolder().add(flushingComponent);
-        ioScheduler.scheduleOperation(new LSMInvertedIndexFlushOperation(new LSMInvertedIndexAccessor(this, lsmHarness,
-                fileManager, opCtx), mutableComponent, componentFileRefs.getInsertIndexFileReference(),
-                componentFileRefs.getDeleteIndexFileReference(), componentFileRefs.getBloomFilterFileReference(),
-                callback));
+        ioScheduler.scheduleOperation(new LSMInvertedIndexFlushOperation(
+                new LSMInvertedIndexAccessor(lsmHarness, opCtx), flushingComponent, componentFileRefs
+                        .getInsertIndexFileReference(), componentFileRefs.getDeleteIndexFileReference(),
+                componentFileRefs.getBloomFilterFileReference(), callback));
         return true;
     }
 
@@ -428,7 +471,8 @@
         IInvertedIndex diskInvertedIndex = component.getInvIndex();
 
         // Create a scan cursor on the BTree underlying the in-memory inverted index.
-        LSMInvertedIndexMutableComponent flushingComponent = flushOp.getFlushingComponent();
+        LSMInvertedIndexMutableComponent flushingComponent = (LSMInvertedIndexMutableComponent) flushOp
+                .getFlushingComponent();
         InMemoryInvertedIndexAccessor memInvIndexAccessor = (InMemoryInvertedIndexAccessor) flushingComponent
                 .getInvIndex().createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
         BTreeAccessor memBTreeAccessor = memInvIndexAccessor.getBTreeAccessor();
@@ -521,7 +565,7 @@
         String lastFileName = lastInvIndex.getBTree().getFileReference().getFile().getName();
 
         LSMComponentFileReferences relMergeFileRefs = fileManager.getRelMergeFileReference(firstFileName, lastFileName);
-        ILSMIndexAccessorInternal accessor = new LSMInvertedIndexAccessor(this, lsmHarness, fileManager, ictx);
+        ILSMIndexAccessorInternal accessor = new LSMInvertedIndexAccessor(lsmHarness, ctx);
         ioScheduler.scheduleOperation(new LSMInvertedIndexMergeOperation(accessor, mergingComponents, cursor,
                 relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getDeleteIndexFileReference(),
                 relMergeFileRefs.getBloomFilterFileReference(), callback));
@@ -574,7 +618,14 @@
     }
 
     public boolean isEmptyIndex() throws HyracksDataException {
-        return componentsRef.get().isEmpty() && !mutableComponent.isModified();
+        boolean isModified = false;
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            if (mutableComponent.isModified()) {
+                isModified = true;
+                break;
+            }
+        }
+        return componentsRef.get().isEmpty() && !isModified;
     }
 
     public class LSMInvertedIndexBulkLoader implements IIndexBulkLoader {
@@ -637,11 +688,11 @@
         }
     }
 
-    protected InMemoryInvertedIndex createInMemoryInvertedIndex(IVirtualBufferCache virtualBufferCache)
-            throws IndexException {
+    protected InMemoryInvertedIndex createInMemoryInvertedIndex(IVirtualBufferCache virtualBufferCache,
+            IVirtualFreePageManager virtualFreePageManager, int id) throws IndexException {
         return InvertedIndexUtils.createInMemoryBTreeInvertedindex(virtualBufferCache, virtualFreePageManager,
                 invListTypeTraits, invListCmpFactories, tokenTypeTraits, tokenCmpFactories, tokenizerFactory,
-                new FileReference(new File(fileManager.getBaseDir() + "_virtual_vocab")));
+                new FileReference(new File(fileManager.getBaseDir() + "_virtual_vocab_" + id)));
     }
 
     protected LSMInvertedIndexImmutableComponent createDiskInvIndexComponent(ILSMComponentFactory factory,
@@ -664,15 +715,13 @@
 
     @Override
     public ILSMIndexAccessorInternal createAccessor(IModificationOperationCallback modificationCallback,
-            ISearchOperationCallback searchCallback) {
-        return new LSMInvertedIndexAccessor(this, lsmHarness, fileManager, createOpContext(modificationCallback,
-                searchCallback));
+            ISearchOperationCallback searchCallback) throws HyracksDataException {
+        return new LSMInvertedIndexAccessor(lsmHarness, createOpContext(modificationCallback, searchCallback));
     }
 
     private LSMInvertedIndexOpContext createOpContext(IModificationOperationCallback modificationCallback,
-            ISearchOperationCallback searchCallback) {
-        return new LSMInvertedIndexOpContext(mutableComponent.getInvIndex(), mutableComponent.getDeletedKeysBTree(),
-                modificationCallback, searchCallback);
+            ISearchOperationCallback searchCallback) throws HyracksDataException {
+        return new LSMInvertedIndexOpContext(mutableComponents, modificationCallback, searchCallback);
     }
 
     @Override
@@ -698,8 +747,12 @@
 
     @Override
     public long getMemoryAllocationSize() {
-        IBufferCache virtualBufferCache = mutableComponent.getInvIndex().getBufferCache();
-        return virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        long size = 0;
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            IBufferCache virtualBufferCache = mutableComponent.getInvIndex().getBufferCache();
+            size += virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        }
+        return size;
     }
 
     @Override
@@ -747,8 +800,10 @@
 
     @Override
     public void validate() throws HyracksDataException {
-        mutableComponent.getInvIndex().validate();
-        mutableComponent.getDeletedKeysBTree().validate();
+        for (LSMInvertedIndexMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getInvIndex().validate();
+            mutableComponent.getDeletedKeysBTree().validate();
+        }
         List<ILSMComponent> immutableComponents = componentsRef.get();
         for (ILSMComponent c : immutableComponents) {
             LSMInvertedIndexImmutableComponent component = (LSMInvertedIndexImmutableComponent) c;
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
index db7529c..e31af9a 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
@@ -25,7 +25,6 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedListCursor;
@@ -33,16 +32,11 @@
 public class LSMInvertedIndexAccessor implements ILSMIndexAccessorInternal, IInvertedIndexAccessor {
 
     protected final ILSMHarness lsmHarness;
-    protected final ILSMIndexFileManager fileManager;
     protected final ILSMIndexOperationContext ctx;
-    protected final LSMInvertedIndex invIndex;
 
-    public LSMInvertedIndexAccessor(LSMInvertedIndex invIndex, ILSMHarness lsmHarness,
-            ILSMIndexFileManager fileManager, ILSMIndexOperationContext ctx) {
+    public LSMInvertedIndexAccessor(ILSMHarness lsmHarness, ILSMIndexOperationContext ctx) {
         this.lsmHarness = lsmHarness;
-        this.fileManager = fileManager;
         this.ctx = ctx;
-        this.invIndex = invIndex;
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
index a8973d1..cf5820e 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
@@ -23,22 +23,22 @@
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 
 public class LSMInvertedIndexFlushOperation implements ILSMIOOperation {
     private final ILSMIndexAccessorInternal accessor;
-    private final LSMInvertedIndexMutableComponent flushingComponent;
+    private final ILSMComponent flushingComponent;
     private final FileReference dictBTreeFlushTarget;
     private final FileReference deletedKeysBTreeFlushTarget;
     private final FileReference bloomFilterFlushTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMInvertedIndexFlushOperation(ILSMIndexAccessorInternal accessor,
-            LSMInvertedIndexMutableComponent flushingComponent, FileReference dictBTreeFlushTarget,
-            FileReference deletedKeysBTreeFlushTarget, FileReference bloomFilterFlushTarget,
-            ILSMIOOperationCallback callback) {
+    public LSMInvertedIndexFlushOperation(ILSMIndexAccessorInternal accessor, ILSMComponent flushingComponent,
+            FileReference dictBTreeFlushTarget, FileReference deletedKeysBTreeFlushTarget,
+            FileReference bloomFilterFlushTarget, ILSMIOOperationCallback callback) {
         this.accessor = accessor;
         this.flushingComponent = flushingComponent;
         this.dictBTreeFlushTarget = dictBTreeFlushTarget;
@@ -84,7 +84,7 @@
         return bloomFilterFlushTarget;
     }
 
-    public LSMInvertedIndexMutableComponent getFlushingComponent() {
+    public ILSMComponent getFlushingComponent() {
         return flushingComponent;
     }
 }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMutableComponent.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMutableComponent.java
index d6c3c5e..72fc3ea 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMutableComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMutableComponent.java
@@ -26,8 +26,9 @@
     private final IInvertedIndex invIndex;
     private final BTree deletedKeysBTree;
 
-    public LSMInvertedIndexMutableComponent(IInvertedIndex invIndex, BTree deletedKeysBTree, IVirtualBufferCache vbc) {
-        super(vbc);
+    public LSMInvertedIndexMutableComponent(IInvertedIndex invIndex, BTree deletedKeysBTree, IVirtualBufferCache vbc,
+            boolean isActive) {
+        super(vbc, isActive);
         this.invIndex = invIndex;
         this.deletedKeysBTree = deletedKeysBTree;
     }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexOpContext.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexOpContext.java
index fd83bfb..95df583 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexOpContext.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexOpContext.java
@@ -19,7 +19,6 @@
 import java.util.List;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
-import edu.uci.ics.hyracks.storage.am.common.api.IIndex;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
@@ -28,7 +27,6 @@
 import edu.uci.ics.hyracks.storage.am.common.tuples.PermutingTupleReference;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
-import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndex;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndexAccessor;
 
 public class LSMInvertedIndexOpContext implements ILSMIndexOperationContext {
@@ -36,8 +34,6 @@
     private static final int NUM_DOCUMENT_FIELDS = 1;
 
     private IndexOperation op;
-    private final IInvertedIndex memInvIndex;
-    private final IIndex memDeletedKeysBTree;
     private final List<ILSMComponent> componentHolder;
 
     public final IModificationOperationCallback modificationCallback;
@@ -46,18 +42,40 @@
     // Tuple that only has the inverted-index elements (aka keys), projecting away the document fields.
     public PermutingTupleReference keysOnlyTuple;
 
-    // Accessor to the in-memory inverted index.
-    public IInvertedIndexAccessor memInvIndexAccessor;
-    // Accessor to the deleted-keys BTree.
-    public IIndexAccessor deletedKeysBTreeAccessor;
+    // Accessor to the in-memory inverted indexes.
+    public IInvertedIndexAccessor[] mutableInvIndexAccessors;
+    // Accessor to the deleted-keys BTrees.
+    public IIndexAccessor[] deletedKeysBTreeAccessors;
 
-    public LSMInvertedIndexOpContext(IInvertedIndex memInvIndex, IIndex memDeletedKeysBTree,
-            IModificationOperationCallback modificationCallback, ISearchOperationCallback searchCallback) {
-        this.memInvIndex = memInvIndex;
-        this.memDeletedKeysBTree = memDeletedKeysBTree;
+    public IInvertedIndexAccessor currentMutableInvIndexAccessors;
+    public IIndexAccessor currentDeletedKeysBTreeAccessors;
+
+    public LSMInvertedIndexOpContext(List<LSMInvertedIndexMutableComponent> mutableComponents,
+            IModificationOperationCallback modificationCallback, ISearchOperationCallback searchCallback)
+            throws HyracksDataException {
         this.componentHolder = new LinkedList<ILSMComponent>();
         this.modificationCallback = modificationCallback;
         this.searchCallback = searchCallback;
+
+        mutableInvIndexAccessors = new IInvertedIndexAccessor[mutableComponents.size()];
+        deletedKeysBTreeAccessors = new IIndexAccessor[mutableComponents.size()];
+
+        for (int i = 0; i < mutableComponents.size(); i++) {
+            mutableInvIndexAccessors[i] = (IInvertedIndexAccessor) mutableComponents.get(i).getInvIndex()
+                    .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            deletedKeysBTreeAccessors[i] = mutableComponents.get(i).getDeletedKeysBTree()
+                    .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+        }
+
+        assert mutableComponents.size() > 0;
+
+        // Project away the document fields, leaving only the key fields.
+        int numKeyFields = mutableComponents.get(0).getInvIndex().getInvListTypeTraits().length;
+        int[] keyFieldPermutation = new int[numKeyFields];
+        for (int i = 0; i < numKeyFields; i++) {
+            keyFieldPermutation[i] = NUM_DOCUMENT_FIELDS + i;
+        }
+        keysOnlyTuple = new PermutingTupleReference(keyFieldPermutation);
     }
 
     @Override
@@ -69,26 +87,6 @@
     // TODO: Ignore opcallback for now.
     public void setOperation(IndexOperation newOp) throws HyracksDataException {
         reset();
-        switch (newOp) {
-            case INSERT:
-            case DELETE:
-            case PHYSICALDELETE: {
-                if (deletedKeysBTreeAccessor == null) {
-                    memInvIndexAccessor = (IInvertedIndexAccessor) memInvIndex.createAccessor(
-                            NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-                    deletedKeysBTreeAccessor = memDeletedKeysBTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                            NoOpOperationCallback.INSTANCE);
-                    // Project away the document fields, leaving only the key fields.
-                    int numKeyFields = memInvIndex.getInvListTypeTraits().length;
-                    int[] keyFieldPermutation = new int[numKeyFields];
-                    for (int i = 0; i < numKeyFields; i++) {
-                        keyFieldPermutation[i] = NUM_DOCUMENT_FIELDS + i;
-                    }
-                    keysOnlyTuple = new PermutingTupleReference(keyFieldPermutation);
-                }
-                break;
-            }
-        }
         op = newOp;
     }
 
@@ -111,4 +109,10 @@
     public IModificationOperationCallback getModificationCallback() {
         return modificationCallback;
     }
+
+    @Override
+    public void setCurrentMutableComponentId(int currentMutableComponentId) {
+        currentMutableInvIndexAccessors = mutableInvIndexAccessors[currentMutableComponentId];
+        currentDeletedKeysBTreeAccessors = deletedKeysBTreeAccessors[currentMutableComponentId];
+    }
 }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexRangeSearchCursor.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexRangeSearchCursor.java
index 820b516..d7911b1 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexRangeSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexRangeSearchCursor.java
@@ -63,7 +63,7 @@
         }
         lsmHarness = lsmInitState.getLSMHarness();
         operationalComponents = lsmInitState.getOperationalComponents();
-        includeMemComponent = lsmInitState.getIncludeMemComponent();
+        includeMutableComponent = lsmInitState.getIncludeMemComponent();
 
         // For searching the deleted-keys BTrees.
         this.keysOnlyTuple = lsmInitState.getKeysOnlyTuple();
@@ -72,7 +72,7 @@
         if (!deletedKeysBTreeAccessors.isEmpty()) {
             deletedKeysBTreeCursors = new IIndexCursor[deletedKeysBTreeAccessors.size()];
             int i = 0;
-            if (includeMemComponent) {
+            if (includeMutableComponent) {
                 // No need for a bloom filter for the in-memory BTree.
                 deletedKeysBTreeCursors[i] = deletedKeysBTreeAccessors.get(i).createSearchCursor();
                 ++i;
@@ -113,7 +113,7 @@
         }
         return false;
     }
-    
+
     @Override
     protected void checkPriorityQueue() throws HyracksDataException, IndexException {
         while (!outputPriorityQueue.isEmpty() || needPush == true) {
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/PartitionedLSMInvertedIndex.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/PartitionedLSMInvertedIndex.java
index 185321b..5b0c48d 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/PartitionedLSMInvertedIndex.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/PartitionedLSMInvertedIndex.java
@@ -16,11 +16,13 @@
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.impls;
 
 import java.io.File;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.storage.am.bloomfilter.impls.BloomFilterFactory;
+import edu.uci.ics.hyracks.storage.am.common.api.IVirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallbackProvider;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
@@ -37,7 +39,7 @@
 
 public class PartitionedLSMInvertedIndex extends LSMInvertedIndex {
 
-    public PartitionedLSMInvertedIndex(IVirtualBufferCache virtualBufferCache,
+    public PartitionedLSMInvertedIndex(List<IVirtualBufferCache> virtualBufferCaches,
             OnDiskInvertedIndexFactory diskInvIndexFactory, BTreeFactory deletedKeysBTreeFactory,
             BloomFilterFactory bloomFilterFactory, double bloomFilterFalsePositiveRate,
             ILSMIndexFileManager fileManager, IFileMapProvider diskFileMapProvider, ITypeTraits[] invListTypeTraits,
@@ -45,17 +47,18 @@
             IBinaryComparatorFactory[] tokenCmpFactories, IBinaryTokenizerFactory tokenizerFactory,
             ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) throws IndexException {
-        super(virtualBufferCache, diskInvIndexFactory, deletedKeysBTreeFactory, bloomFilterFactory,
+        super(virtualBufferCaches, diskInvIndexFactory, deletedKeysBTreeFactory, bloomFilterFactory,
                 bloomFilterFalsePositiveRate, fileManager, diskFileMapProvider, invListTypeTraits, invListCmpFactories,
                 tokenTypeTraits, tokenCmpFactories, tokenizerFactory, mergePolicy, opTracker, ioScheduler,
                 ioOpCallbackProvider);
     }
 
-    protected InMemoryInvertedIndex createInMemoryInvertedIndex(IVirtualBufferCache virtualBufferCache)
-            throws IndexException {
+    @Override
+    protected InMemoryInvertedIndex createInMemoryInvertedIndex(IVirtualBufferCache virtualBufferCache,
+            IVirtualFreePageManager virtualFreePageManager, int id) throws IndexException {
         return InvertedIndexUtils.createPartitionedInMemoryBTreeInvertedindex(virtualBufferCache,
                 virtualFreePageManager, invListTypeTraits, invListCmpFactories, tokenTypeTraits, tokenCmpFactories,
-                tokenizerFactory, new FileReference(new File(fileManager.getBaseDir() + "_virtual_vocab")));
+                tokenizerFactory, new FileReference(new File(fileManager.getBaseDir() + "_virtual_vocab_" + id)));
     }
 
 }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/InvertedIndexUtils.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/InvertedIndexUtils.java
index 9d85f56..ed02ba1 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/InvertedIndexUtils.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/InvertedIndexUtils.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.util;
 
 import java.io.File;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
@@ -115,7 +116,7 @@
         return deletedKeysBTreeFactory;
     }
 
-    public static LSMInvertedIndex createLSMInvertedIndex(IVirtualBufferCache virtualBufferCache,
+    public static LSMInvertedIndex createLSMInvertedIndex(List<IVirtualBufferCache> virtualBufferCaches,
             IFileMapProvider diskFileMapProvider, ITypeTraits[] invListTypeTraits,
             IBinaryComparatorFactory[] invListCmpFactories, ITypeTraits[] tokenTypeTraits,
             IBinaryComparatorFactory[] tokenCmpFactories, IBinaryTokenizerFactory tokenizerFactory,
@@ -143,20 +144,21 @@
                 diskFileMapProvider, invListBuilderFactory, invListTypeTraits, invListCmpFactories, tokenTypeTraits,
                 tokenCmpFactories, fileManager);
 
-        LSMInvertedIndex invIndex = new LSMInvertedIndex(virtualBufferCache, invIndexFactory, deletedKeysBTreeFactory,
+        LSMInvertedIndex invIndex = new LSMInvertedIndex(virtualBufferCaches, invIndexFactory, deletedKeysBTreeFactory,
                 bloomFilterFactory, bloomFilterFalsePositiveRate, fileManager, diskFileMapProvider, invListTypeTraits,
                 invListCmpFactories, tokenTypeTraits, tokenCmpFactories, tokenizerFactory, mergePolicy, opTracker,
                 ioScheduler, ioOpCallbackProvider);
         return invIndex;
     }
 
-    public static PartitionedLSMInvertedIndex createPartitionedLSMInvertedIndex(IVirtualBufferCache virtualBufferCache,
-            IFileMapProvider diskFileMapProvider, ITypeTraits[] invListTypeTraits,
-            IBinaryComparatorFactory[] invListCmpFactories, ITypeTraits[] tokenTypeTraits,
-            IBinaryComparatorFactory[] tokenCmpFactories, IBinaryTokenizerFactory tokenizerFactory,
-            IBufferCache diskBufferCache, String onDiskDir, double bloomFilterFalsePositiveRate,
-            ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
-            ILSMIOOperationCallbackProvider ioOpCallbackProvider) throws IndexException {
+    public static PartitionedLSMInvertedIndex createPartitionedLSMInvertedIndex(
+            List<IVirtualBufferCache> virtualBufferCaches, IFileMapProvider diskFileMapProvider,
+            ITypeTraits[] invListTypeTraits, IBinaryComparatorFactory[] invListCmpFactories,
+            ITypeTraits[] tokenTypeTraits, IBinaryComparatorFactory[] tokenCmpFactories,
+            IBinaryTokenizerFactory tokenizerFactory, IBufferCache diskBufferCache, String onDiskDir,
+            double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker,
+            ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider)
+            throws IndexException {
 
         BTreeFactory deletedKeysBTreeFactory = createDeletedKeysBTreeFactory(diskFileMapProvider, invListTypeTraits,
                 invListCmpFactories, diskBufferCache);
@@ -178,7 +180,7 @@
                 diskBufferCache, diskFileMapProvider, invListBuilderFactory, invListTypeTraits, invListCmpFactories,
                 tokenTypeTraits, tokenCmpFactories, fileManager);
 
-        PartitionedLSMInvertedIndex invIndex = new PartitionedLSMInvertedIndex(virtualBufferCache, invIndexFactory,
+        PartitionedLSMInvertedIndex invIndex = new PartitionedLSMInvertedIndex(virtualBufferCaches, invIndexFactory,
                 deletedKeysBTreeFactory, bloomFilterFactory, bloomFilterFalsePositiveRate, fileManager,
                 diskFileMapProvider, invListTypeTraits, invListCmpFactories, tokenTypeTraits, tokenCmpFactories,
                 tokenizerFactory, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider);
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/AbstractLSMRTreeDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/AbstractLSMRTreeDataflowHelper.java
index 9fc8cea..5d57aae 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/AbstractLSMRTreeDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/AbstractLSMRTreeDataflowHelper.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
@@ -44,24 +46,24 @@
     protected final ILinearizeComparatorFactory linearizeCmpFactory;
 
     public AbstractLSMRTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, IBinaryComparatorFactory[] btreeComparatorFactories,
+            List<IVirtualBufferCache> virtualBufferCaches, IBinaryComparatorFactory[] btreeComparatorFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider,
             ILinearizeComparatorFactory linearizeCmpFactory) {
-        this(opDesc, ctx, partition, virtualBufferCache, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE,
+        this(opDesc, ctx, partition, virtualBufferCaches, DEFAULT_BLOOM_FILTER_FALSE_POSITIVE_RATE,
                 btreeComparatorFactories, valueProviderFactories, rtreePolicyType, mergePolicy, opTrackerFactory,
                 ioScheduler, ioOpCallbackProvider, linearizeCmpFactory);
     }
 
     public AbstractLSMRTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate,
+            List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate,
             IBinaryComparatorFactory[] btreeComparatorFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider,
             ILinearizeComparatorFactory linearizeCmpFactory) {
-        super(opDesc, ctx, partition, virtualBufferCache, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
+        super(opDesc, ctx, partition, virtualBufferCaches, bloomFilterFalsePositiveRate, mergePolicy, opTrackerFactory,
                 ioScheduler, ioOpCallbackProvider);
         this.btreeComparatorFactories = btreeComparatorFactories;
         this.valueProviderFactories = valueProviderFactories;
@@ -72,14 +74,14 @@
     @Override
     public ITreeIndex createIndexInstance() throws HyracksDataException {
         AbstractTreeIndexOperatorDescriptor treeOpDesc = (AbstractTreeIndexOperatorDescriptor) opDesc;
-        return createLSMTree(virtualBufferCache, file, opDesc.getStorageManager().getBufferCache(ctx), opDesc
+        return createLSMTree(virtualBufferCaches, file, opDesc.getStorageManager().getBufferCache(ctx), opDesc
                 .getStorageManager().getFileMapProvider(ctx), treeOpDesc.getTreeIndexTypeTraits(),
                 treeOpDesc.getTreeIndexComparatorFactories(), btreeComparatorFactories,
                 opTrackerFactory.getOperationTracker(ctx), valueProviderFactories, rtreePolicyType, linearizeCmpFactory);
 
     }
 
-    protected abstract ITreeIndex createLSMTree(IVirtualBufferCache virtualBufferCache, FileReference file,
+    protected abstract ITreeIndex createLSMTree(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
             ILSMOperationTracker opTracker, IPrimitiveValueProviderFactory[] valueProviderFactories,
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelper.java
index b47bc02..bc4bca3 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelper.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
@@ -39,36 +41,36 @@
 public class LSMRTreeDataflowHelper extends AbstractLSMRTreeDataflowHelper {
 
     public LSMRTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, IBinaryComparatorFactory[] btreeComparatorFactories,
+            List<IVirtualBufferCache> virtualBufferCaches, IBinaryComparatorFactory[] btreeComparatorFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider,
             ILinearizeComparatorFactory linearizeCmpFactory) {
-        super(opDesc, ctx, partition, virtualBufferCache, btreeComparatorFactories, valueProviderFactories,
+        super(opDesc, ctx, partition, virtualBufferCaches, btreeComparatorFactories, valueProviderFactories,
                 rtreePolicyType, mergePolicy, opTrackerFactory, ioScheduler, ioOpCallbackProvider, linearizeCmpFactory);
     }
 
     public LSMRTreeDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx, int partition,
-            IVirtualBufferCache virtualBufferCache, double bloomFilterFalsePositiveRate,
+            List<IVirtualBufferCache> virtualBufferCaches, double bloomFilterFalsePositiveRate,
             IBinaryComparatorFactory[] btreeComparatorFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider,
             ILinearizeComparatorFactory linearizeCmpFactory) {
-        super(opDesc, ctx, partition, virtualBufferCache, bloomFilterFalsePositiveRate, btreeComparatorFactories,
+        super(opDesc, ctx, partition, virtualBufferCaches, bloomFilterFalsePositiveRate, btreeComparatorFactories,
                 valueProviderFactories, rtreePolicyType, mergePolicy, opTrackerFactory, ioScheduler,
                 ioOpCallbackProvider, linearizeCmpFactory);
     }
 
     @Override
-    protected ITreeIndex createLSMTree(IVirtualBufferCache virtualBufferCache, FileReference file,
+    protected ITreeIndex createLSMTree(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
             ILSMOperationTracker opTracker, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType, ILinearizeComparatorFactory linearizeCmpFactory)
             throws HyracksDataException {
         try {
-            return LSMRTreeUtils.createLSMTree(virtualBufferCache, file, diskBufferCache, diskFileMapProvider,
+            return LSMRTreeUtils.createLSMTree(virtualBufferCaches, file, diskBufferCache, diskFileMapProvider,
                     typeTraits, rtreeCmpFactories, btreeCmpFactories, valueProviderFactories, rtreePolicyType,
                     bloomFilterFalsePositiveRate, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider,
                     linearizeCmpFactory);
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelperFactory.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelperFactory.java
index 5d35bc5..99b4219 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelperFactory.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeDataflowHelperFactory.java
@@ -56,7 +56,7 @@
     public IndexDataflowHelper createIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
             int partition) {
         return new LSMRTreeDataflowHelper(opDesc, ctx, partition,
-                virtualBufferCacheProvider.getVirtualBufferCache(ctx), bloomFilterFalsePositiveRate,
+                virtualBufferCacheProvider.getVirtualBufferCaches(ctx), bloomFilterFalsePositiveRate,
                 btreeComparatorFactories, valueProviderFactories, rtreePolicyType,
                 mergePolicyProvider.getMergePolicy(ctx), opTrackerFactory, ioSchedulerProvider.getIOScheduler(ctx),
                 ioOpCallbackProvider, linearizeCmpFactory);
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelper.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelper.java
index ea1b1e2..72f3480 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelper.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelper.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.dataflow;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
@@ -38,24 +40,24 @@
 
 public class LSMRTreeWithAntiMatterTuplesDataflowHelper extends AbstractLSMRTreeDataflowHelper {
     public LSMRTreeWithAntiMatterTuplesDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
-            int partition, IVirtualBufferCache virtualBufferCache, IBinaryComparatorFactory[] btreeComparatorFactories,
+            int partition, List<IVirtualBufferCache> virtualBufferCaches, IBinaryComparatorFactory[] btreeComparatorFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
             ILSMMergePolicy mergePolicy, ILSMOperationTrackerProvider opTrackerFactory,
             ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider,
             ILinearizeComparatorFactory linearizeCmpFactory) {
-        super(opDesc, ctx, partition, virtualBufferCache, btreeComparatorFactories, valueProviderFactories,
+        super(opDesc, ctx, partition, virtualBufferCaches, btreeComparatorFactories, valueProviderFactories,
                 rtreePolicyType, mergePolicy, opTrackerFactory, ioScheduler, ioOpCallbackProvider, linearizeCmpFactory);
     }
 
     @Override
-    protected ITreeIndex createLSMTree(IVirtualBufferCache virtualBufferCache, FileReference file,
+    protected ITreeIndex createLSMTree(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
             ILSMOperationTracker opTracker, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType, ILinearizeComparatorFactory linearizeCmpFactory)
             throws HyracksDataException {
         try {
-            return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(virtualBufferCache, file, diskBufferCache,
+            return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(virtualBufferCaches, file, diskBufferCache,
                     diskFileMapProvider, typeTraits, rtreeCmpFactories, btreeCmpFactories, valueProviderFactories,
                     rtreePolicyType, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider, linearizeCmpFactory);
         } catch (TreeIndexException e) {
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelperFactory.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelperFactory.java
index 5fca08f..00268b3 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelperFactory.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/dataflow/LSMRTreeWithAntiMatterTuplesDataflowHelperFactory.java
@@ -63,7 +63,7 @@
     public IndexDataflowHelper createIndexDataflowHelper(IIndexOperatorDescriptor opDesc, IHyracksTaskContext ctx,
             int partition) {
         return new LSMRTreeWithAntiMatterTuplesDataflowHelper(opDesc, ctx, partition,
-                virtualBufferCacheProvider.getVirtualBufferCache(ctx), btreeComparatorFactories,
+                virtualBufferCacheProvider.getVirtualBufferCaches(ctx), btreeComparatorFactories,
                 valueProviderFactories, rtreePolicyType, mergePolicyProvider.getMergePolicy(ctx), opTrackerProvider,
                 ioSchedulerProvider.getIOScheduler(ctx), ioOpCallbackProvider, linearizeCmpFactory);
     }
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
index 31a2773..5ee6cb0 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
@@ -24,17 +25,16 @@
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
-import edu.uci.ics.hyracks.storage.am.btree.impls.BTree.BTreeAccessor;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.IFreePageManager;
+import edu.uci.ics.hyracks.storage.am.common.api.IIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
+import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndex;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrameFactory;
-import edu.uci.ics.hyracks.storage.am.common.api.IVirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexDuplicateKeyException;
 import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
@@ -47,6 +47,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.IMutableComponentSwitcherCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.freepage.VirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractLSMIndex;
@@ -56,7 +57,6 @@
 import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeInteriorFrame;
 import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeLeafFrame;
 import edu.uci.ics.hyracks.storage.am.rtree.impls.RTree;
-import edu.uci.ics.hyracks.storage.am.rtree.impls.RTree.RTreeAccessor;
 import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
 import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;
 
@@ -67,9 +67,7 @@
     protected final IBinaryComparatorFactory[] linearizerArray;
 
     // In-memory components.
-    protected final LSMRTreeMutableComponent mutableComponent;
-    protected final IVirtualBufferCache virtualBufferCache;
-    protected final IVirtualFreePageManager virtualFreePageManager;
+    protected final List<LSMRTreeMutableComponent> mutableComponents;
 
     protected TreeTupleSorter rTreeTupleSorter;
 
@@ -86,27 +84,53 @@
     protected final ITreeIndexFrameFactory rtreeLeafFrameFactory;
     protected final ITreeIndexFrameFactory btreeLeafFrameFactory;
 
-    public AbstractLSMRTree(IVirtualBufferCache virtualBufferCache, ITreeIndexFrameFactory rtreeInteriorFrameFactory,
-            ITreeIndexFrameFactory rtreeLeafFrameFactory, ITreeIndexFrameFactory btreeInteriorFrameFactory,
-            ITreeIndexFrameFactory btreeLeafFrameFactory, ILSMIndexFileManager fileManager,
-            TreeIndexFactory<RTree> diskRTreeFactory, ILSMComponentFactory componentFactory,
-            IFileMapProvider diskFileMapProvider, int fieldCount, IBinaryComparatorFactory[] rtreeCmpFactories,
-            IBinaryComparatorFactory[] btreeCmpFactories, ILinearizeComparatorFactory linearizer,
-            int[] comparatorFields, IBinaryComparatorFactory[] linearizerArray, double bloomFilterFalsePositiveRate,
-            ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
-            ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(virtualBufferCache, diskRTreeFactory.getBufferCache(), fileManager, diskFileMapProvider,
+    public AbstractLSMRTree(List<IVirtualBufferCache> virtualBufferCaches,
+            ITreeIndexFrameFactory rtreeInteriorFrameFactory, ITreeIndexFrameFactory rtreeLeafFrameFactory,
+            ITreeIndexFrameFactory btreeInteriorFrameFactory, ITreeIndexFrameFactory btreeLeafFrameFactory,
+            ILSMIndexFileManager fileManager, TreeIndexFactory<RTree> diskRTreeFactory,
+            ILSMComponentFactory componentFactory, IFileMapProvider diskFileMapProvider, int fieldCount,
+            IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
+            ILinearizeComparatorFactory linearizer, int[] comparatorFields, IBinaryComparatorFactory[] linearizerArray,
+            double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker,
+            ILSMIOOperationScheduler ioScheduler, ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
+        super(virtualBufferCaches, diskRTreeFactory.getBufferCache(), fileManager, diskFileMapProvider,
                 bloomFilterFalsePositiveRate, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider);
-        virtualFreePageManager = new VirtualFreePageManager(virtualBufferCache.getNumPages());
-        RTree memRTree = new RTree(virtualBufferCache, ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(),
-                virtualFreePageManager, rtreeInteriorFrameFactory, rtreeLeafFrameFactory, rtreeCmpFactories,
-                fieldCount, new FileReference(new File(fileManager.getBaseDir() + "_virtual_r")));
-        BTree memBTree = new BTree(virtualBufferCache, ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(),
-                new VirtualFreePageManager(virtualBufferCache.getNumPages()), btreeInteriorFrameFactory,
-                btreeLeafFrameFactory, btreeCmpFactories, fieldCount, new FileReference(new File(
-                        fileManager.getBaseDir() + "_virtual_b")));
-        mutableComponent = new LSMRTreeMutableComponent(memRTree, memBTree, virtualBufferCache);
-        this.virtualBufferCache = virtualBufferCache;
+
+        mutableComponents = new ArrayList<LSMRTreeMutableComponent>();
+        final int numMutableComponents = virtualBufferCaches.size();
+        int i = 0;
+        for (IVirtualBufferCache virtualBufferCache : virtualBufferCaches) {
+            RTree memRTree = new RTree(virtualBufferCache,
+                    ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(), new VirtualFreePageManager(
+                            virtualBufferCache.getNumPages()), rtreeInteriorFrameFactory, rtreeLeafFrameFactory,
+                    rtreeCmpFactories, fieldCount, new FileReference(new File(fileManager.getBaseDir() + "_virtual_r_"
+                            + i)));
+            BTree memBTree = new BTree(virtualBufferCache,
+                    ((IVirtualBufferCache) virtualBufferCache).getFileMapProvider(), new VirtualFreePageManager(
+                            virtualBufferCache.getNumPages()), btreeInteriorFrameFactory, btreeLeafFrameFactory,
+                    btreeCmpFactories, fieldCount, new FileReference(new File(fileManager.getBaseDir() + "_virtual_b_"
+                            + i)));
+            LSMRTreeMutableComponent mutableComponent = new LSMRTreeMutableComponent(memRTree, memBTree,
+                    virtualBufferCache, i == 0 ? true : false);
+
+            mutableComponent.registerOnFlushCallback(new IMutableComponentSwitcherCallback() {
+
+                @Override
+                public void switchComponents() throws HyracksDataException {
+                    currentMutableComponentId.set((currentMutableComponentId.get() + 1) % numMutableComponents);
+                    mutableComponents.get(currentMutableComponentId.get()).setActive();
+                }
+
+                @Override
+                public void setFlushStatus(boolean isFlushNeeded) {
+                    needsFlush[currentMutableComponentId.get()].set(isFlushNeeded);
+                }
+            });
+
+            mutableComponents.add(mutableComponent);
+            ++i;
+        }
+
         this.rtreeInteriorFrameFactory = rtreeInteriorFrameFactory;
         this.rtreeLeafFrameFactory = rtreeLeafFrameFactory;
         this.btreeInteriorFrameFactory = btreeInteriorFrameFactory;
@@ -137,11 +161,13 @@
             throw new HyracksDataException("Failed to activate the index since it is already activated.");
         }
 
-        ((IVirtualBufferCache) mutableComponent.getRTree().getBufferCache()).open();
-        mutableComponent.getRTree().create();
-        mutableComponent.getBTree().create();
-        mutableComponent.getRTree().activate();
-        mutableComponent.getBTree().activate();
+        for (LSMRTreeMutableComponent mutableComponent : mutableComponents) {
+            ((IVirtualBufferCache) mutableComponent.getRTree().getBufferCache()).open();
+            mutableComponent.getRTree().create();
+            mutableComponent.getBTree().create();
+            mutableComponent.getRTree().activate();
+            mutableComponent.getBTree().activate();
+        }
     }
 
     @Override
@@ -163,11 +189,13 @@
             }
         }
 
-        mutableComponent.getRTree().deactivate();
-        mutableComponent.getBTree().deactivate();
-        mutableComponent.getRTree().destroy();
-        mutableComponent.getBTree().destroy();
-        ((IVirtualBufferCache) mutableComponent.getRTree().getBufferCache()).close();
+        for (LSMRTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getRTree().deactivate();
+            mutableComponent.getBTree().deactivate();
+            mutableComponent.getRTree().destroy();
+            mutableComponent.getBTree().destroy();
+            ((IVirtualBufferCache) mutableComponent.getRTree().getBufferCache()).close();
+        }
     }
 
     @Override
@@ -183,14 +211,11 @@
             throw new HyracksDataException("Failed to clear the index since it is not activated.");
         }
 
-        mutableComponent.getRTree().clear();
-        mutableComponent.getBTree().clear();
-        mutableComponent.reset();
-    }
-
-    @Override
-    public ILSMComponent getMutableComponent() {
-        return mutableComponent;
+        for (LSMRTreeMutableComponent mutableComponent : mutableComponents) {
+            mutableComponent.getRTree().clear();
+            mutableComponent.getBTree().clear();
+            mutableComponent.reset();
+        }
     }
 
     @Override
@@ -198,14 +223,26 @@
         List<ILSMComponent> operationalComponents = ctx.getComponentHolder();
         operationalComponents.clear();
         List<ILSMComponent> immutableComponents = componentsRef.get();
+        int cmc = currentMutableComponentId.get();
+        ctx.setCurrentMutableComponentId(cmc);
+        int numMutableComponents = mutableComponents.size();
         switch (ctx.getOperation()) {
             case INSERT:
             case DELETE:
             case FLUSH:
-                operationalComponents.add(mutableComponent);
+                operationalComponents.add(mutableComponents.get(cmc));
                 break;
             case SEARCH:
-                operationalComponents.add(mutableComponent);
+                for (int i = 0; i < numMutableComponents - 1; i++) {
+                    LSMRTreeMutableComponent mutableComponent = mutableComponents.get((cmc + i + 1)
+                            % numMutableComponents);
+                    if (mutableComponent.isReadable()) {
+                        // Make sure newest components are added first
+                        operationalComponents.add(0, mutableComponent);
+                    }
+                }
+                // The current mutable component is always added
+                operationalComponents.add(0, mutableComponents.get(cmc));
                 operationalComponents.addAll(immutableComponents);
                 break;
             case MERGE:
@@ -216,6 +253,19 @@
         }
     }
 
+    @Override
+    public void search(ILSMIndexOperationContext ictx, IIndexCursor cursor, ISearchPredicate pred)
+            throws HyracksDataException, IndexException {
+        LSMRTreeOpContext ctx = (LSMRTreeOpContext) ictx;
+        List<ILSMComponent> operationalComponents = ictx.getComponentHolder();
+
+        LSMRTreeCursorInitialState initialState = new LSMRTreeCursorInitialState(rtreeLeafFrameFactory,
+                rtreeInteriorFrameFactory, btreeLeafFrameFactory, ctx.getBTreeMultiComparator(), lsmHarness,
+                comparatorFields, linearizerArray, ctx.searchCallback, operationalComponents);
+
+        cursor.open(initialState, pred);
+    }
+
     protected LSMComponentFileReferences getMergeTargetFileName(List<ILSMComponent> mergingDiskComponents)
             throws HyracksDataException {
         RTree firstTree = ((LSMRTreeImmutableComponent) mergingDiskComponents.get(0)).getRTree();
@@ -253,32 +303,32 @@
 
     @Override
     public ITreeIndexFrameFactory getLeafFrameFactory() {
-        return mutableComponent.getRTree().getLeafFrameFactory();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getLeafFrameFactory();
     }
 
     @Override
     public ITreeIndexFrameFactory getInteriorFrameFactory() {
-        return mutableComponent.getRTree().getInteriorFrameFactory();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getInteriorFrameFactory();
     }
 
     @Override
     public IFreePageManager getFreePageManager() {
-        return mutableComponent.getRTree().getFreePageManager();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getFreePageManager();
     }
 
     @Override
     public int getFieldCount() {
-        return mutableComponent.getRTree().getFieldCount();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getFieldCount();
     }
 
     @Override
     public int getRootPageId() {
-        return mutableComponent.getRTree().getRootPageId();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getRootPageId();
     }
 
     @Override
     public int getFileId() {
-        return mutableComponent.getRTree().getFileId();
+        return mutableComponents.get(currentMutableComponentId.get()).getRTree().getFileId();
     }
 
     @Override
@@ -298,8 +348,8 @@
             // added RTree tuple.
             RangePredicate btreeRangePredicate = new RangePredicate(tuple, tuple, true, true,
                     ctx.getBTreeMultiComparator(), ctx.getBTreeMultiComparator());
-            ITreeIndexCursor cursor = ctx.memBTreeAccessor.createSearchCursor();
-            ctx.memBTreeAccessor.search(cursor, btreeRangePredicate);
+            ITreeIndexCursor cursor = ctx.currentMutableBTreeAccessor.createSearchCursor();
+            ctx.currentMutableBTreeAccessor.search(cursor, btreeRangePredicate);
             boolean foundTupleInMemoryBTree = false;
             try {
                 if (cursor.hasNext()) {
@@ -310,7 +360,7 @@
             }
             if (foundTupleInMemoryBTree) {
                 try {
-                    ctx.memBTreeAccessor.delete(tuple);
+                    ctx.currentMutableBTreeAccessor.delete(tuple);
                 } catch (TreeIndexNonExistentKeyException e) {
                     // Tuple has been deleted in the meantime. Do nothing.
                     // This normally shouldn't happen if we are dealing with
@@ -319,31 +369,25 @@
                     // insert between them.
                 }
             } else {
-                ctx.memRTreeAccessor.insert(tuple);
+                ctx.currentMutableRTreeAccessor.insert(tuple);
             }
 
         } else {
             try {
-                ctx.memBTreeAccessor.insert(tuple);
-            } catch (TreeIndexDuplicateKeyException e) {
+                ctx.currentMutableBTreeAccessor.insert(tuple);
+            } catch (TreeIndexNonExistentKeyException e) {
                 // Do nothing, because one delete tuple is enough to indicate
                 // that all the corresponding insert tuples are deleted
             }
         }
-        mutableComponent.setIsModified();
+        mutableComponents.get(currentMutableComponentId.get()).setIsModified();
     }
 
     protected LSMRTreeOpContext createOpContext(IModificationOperationCallback modCallback) {
-        RTreeAccessor rtreeAccessor = (RTree.RTreeAccessor) mutableComponent.getRTree().createAccessor(
-                NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-        BTreeAccessor btreeAccessor = (BTree.BTreeAccessor) mutableComponent.getBTree().createAccessor(
-                NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-
-        return new LSMRTreeOpContext(rtreeAccessor, (IRTreeLeafFrame) rtreeLeafFrameFactory.createFrame(),
-                (IRTreeInteriorFrame) rtreeInteriorFrameFactory.createFrame(), virtualFreePageManager
-                        .getMetaDataFrameFactory().createFrame(), 4, btreeAccessor, btreeLeafFrameFactory,
-                btreeInteriorFrameFactory, virtualFreePageManager.getMetaDataFrameFactory().createFrame(),
-                rtreeCmpFactories, btreeCmpFactories, modCallback, NoOpOperationCallback.INSTANCE);
+        return new LSMRTreeOpContext(mutableComponents, (IRTreeLeafFrame) rtreeLeafFrameFactory.createFrame(),
+                (IRTreeInteriorFrame) rtreeInteriorFrameFactory.createFrame(), btreeLeafFrameFactory,
+                btreeInteriorFrameFactory, rtreeCmpFactories, btreeCmpFactories, modCallback,
+                NoOpOperationCallback.INSTANCE);
     }
 
     @Override
@@ -352,7 +396,14 @@
     }
 
     public boolean isEmptyIndex() throws HyracksDataException {
-        return componentsRef.get().isEmpty() && !mutableComponent.isModified();
+        boolean isModified = false;
+        for (LSMRTreeMutableComponent mutableComponent : mutableComponents) {
+            if (mutableComponent.isModified()) {
+                isModified = true;
+                break;
+            }
+        }
+        return componentsRef.get().isEmpty() && !isModified;
     }
 
     @Override
@@ -362,8 +413,12 @@
 
     @Override
     public long getMemoryAllocationSize() {
-        IBufferCache virtualBufferCache = mutableComponent.getRTree().getBufferCache();
-        return virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        long size = 0;
+        for (LSMRTreeMutableComponent mutableComponent : mutableComponents) {
+            IBufferCache virtualBufferCache = mutableComponent.getRTree().getBufferCache();
+            size += virtualBufferCache.getNumPages() * virtualBufferCache.getPageSize();
+        }
+        return size;
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
index 0b71373..ef91e7a 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
@@ -16,7 +16,6 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
 
 import java.util.List;
-import java.util.ListIterator;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
@@ -55,6 +54,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractMutableLSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMTreeIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.TreeIndexFactory;
@@ -66,7 +66,7 @@
 
 public class LSMRTree extends AbstractLSMRTree {
 
-    public LSMRTree(IVirtualBufferCache virtualBufferCache, ITreeIndexFrameFactory rtreeInteriorFrameFactory,
+    public LSMRTree(List<IVirtualBufferCache> virtualBufferCaches, ITreeIndexFrameFactory rtreeInteriorFrameFactory,
             ITreeIndexFrameFactory rtreeLeafFrameFactory, ITreeIndexFrameFactory btreeInteriorFrameFactory,
             ITreeIndexFrameFactory btreeLeafFrameFactory, ILSMIndexFileManager fileNameManager,
             TreeIndexFactory<RTree> diskRTreeFactory, TreeIndexFactory<BTree> diskBTreeFactory,
@@ -76,7 +76,7 @@
             int[] comparatorFields, IBinaryComparatorFactory[] linearizerArray, ILSMMergePolicy mergePolicy,
             ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(virtualBufferCache, rtreeInteriorFrameFactory, rtreeLeafFrameFactory, btreeInteriorFrameFactory,
+        super(virtualBufferCaches, rtreeInteriorFrameFactory, rtreeLeafFrameFactory, btreeInteriorFrameFactory,
                 btreeLeafFrameFactory, fileNameManager, diskRTreeFactory, new LSMRTreeComponentFactory(
                         diskRTreeFactory, diskBTreeFactory, bloomFilterFactory), diskFileMapProvider, fieldCount,
                 rtreeCmpFactories, btreeCmpFactories, linearizer, comparatorFields, linearizerArray,
@@ -168,51 +168,14 @@
     }
 
     @Override
-    public void search(ILSMIndexOperationContext ictx, IIndexCursor cursor, ISearchPredicate pred)
-            throws HyracksDataException, IndexException {
-        LSMRTreeOpContext ctx = (LSMRTreeOpContext) ictx;
-        List<ILSMComponent> operationalComponents = ctx.getComponentHolder();
-        boolean includeMutableComponent = operationalComponents.get(0) == mutableComponent;
-        int numTrees = operationalComponents.size();
-
-        ListIterator<ILSMComponent> diskComponentIter = operationalComponents.listIterator();
-        ITreeIndexAccessor[] rTreeAccessors = new ITreeIndexAccessor[numTrees];
-        ITreeIndexAccessor[] bTreeAccessors = new ITreeIndexAccessor[numTrees];
-        int diskComponentIx = 0;
-        if (includeMutableComponent) {
-            rTreeAccessors[0] = ctx.memRTreeAccessor;
-            bTreeAccessors[0] = ctx.memBTreeAccessor;
-            diskComponentIx++;
-            diskComponentIter.next();
-        }
-
-        while (diskComponentIter.hasNext()) {
-            LSMRTreeImmutableComponent component = (LSMRTreeImmutableComponent) diskComponentIter.next();
-            RTree diskRTree = component.getRTree();
-            BTree diskBTree = component.getBTree();
-            rTreeAccessors[diskComponentIx] = diskRTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            bTreeAccessors[diskComponentIx] = diskBTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            diskComponentIx++;
-        }
-
-        LSMRTreeCursorInitialState initialState = new LSMRTreeCursorInitialState(numTrees, rtreeLeafFrameFactory,
-                rtreeInteriorFrameFactory, btreeLeafFrameFactory, ctx.getBTreeMultiComparator(), rTreeAccessors,
-                bTreeAccessors, includeMutableComponent, lsmHarness, comparatorFields, linearizerArray,
-                ctx.searchCallback, operationalComponents);
-        cursor.open(initialState, pred);
-    }
-
-    @Override
     public boolean scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        if (!mutableComponent.isModified()) {
+        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
+        if (!((AbstractMutableLSMComponent) flushingComponent).isModified()) {
             return false;
         }
         LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
         ILSMIndexOperationContext rctx = createOpContext(NoOpOperationCallback.INSTANCE);
-        LSMRTreeMutableComponent flushingComponent = (LSMRTreeMutableComponent) ctx.getComponentHolder().get(0);
         rctx.setOperation(IndexOperation.FLUSH);
         rctx.getComponentHolder().addAll(ctx.getComponentHolder());
         LSMRTreeAccessor accessor = new LSMRTreeAccessor(lsmHarness, rctx);
@@ -255,6 +218,9 @@
             while (rtreeScanCursor.hasNext()) {
                 isEmpty = false;
                 rtreeScanCursor.next();
+                if (rtreeScanCursor.getPageId() == 0) {
+                    System.out.println();
+                }
                 rTreeTupleSorter.insertTupleEntry(rtreeScanCursor.getPageId(), rtreeScanCursor.getTupleOffset());
             }
         } finally {
@@ -329,9 +295,6 @@
     @Override
     public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException, IndexException {
-        // Renaming order is critical because we use assume ordering when we
-        // read the file names when we open the tree.
-        // The RTree should be renamed before the BTree.
         List<ILSMComponent> mergingComponents = ctx.getComponentHolder();
         ILSMIndexOperationContext rctx = createOpContext(NoOpOperationCallback.INSTANCE);
         rctx.getComponentHolder().addAll(mergingComponents);
@@ -389,7 +352,7 @@
 
         public MultiComparator getMultiComparator() {
             LSMRTreeOpContext concreteCtx = (LSMRTreeOpContext) ctx;
-            return concreteCtx.rtreeOpContext.cmp;
+            return concreteCtx.currentRTreeOpContext.cmp;
         }
     }
 
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeAbstractCursor.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeAbstractCursor.java
index 0cd578a..279b777 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeAbstractCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeAbstractCursor.java
@@ -12,146 +12,155 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
-
-import java.util.List;
-
-import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
-import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
-import edu.uci.ics.hyracks.storage.am.btree.api.IBTreeLeafFrame;
-import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeRangeSearchCursor;
-import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
-import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
-import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
-import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexAccessor;
-import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
-import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMHarness;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
-import edu.uci.ics.hyracks.storage.am.lsm.common.impls.BloomFilterAwareBTreePointSearchCursor;
-import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeInteriorFrame;
-import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeLeafFrame;
-import edu.uci.ics.hyracks.storage.am.rtree.impls.RTreeSearchCursor;
-import edu.uci.ics.hyracks.storage.am.rtree.impls.SearchPredicate;
-import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
-import edu.uci.ics.hyracks.storage.common.buffercache.ICachedPage;
-
-public abstract class LSMRTreeAbstractCursor implements ITreeIndexCursor {
-
-    protected RTreeSearchCursor[] rtreeCursors;
-    protected boolean open = false;
-    protected ITreeIndexCursor[] btreeCursors;
-    protected ITreeIndexAccessor[] rTreeAccessors;
-    protected ITreeIndexAccessor[] bTreeAccessors;
-    private MultiComparator btreeCmp;
-    protected int numberOfTrees;
-    protected SearchPredicate rtreeSearchPredicate;
-    protected RangePredicate btreeRangePredicate;
-    protected ITupleReference frameTuple;
-    protected boolean includeMemRTree;
-    protected ILSMHarness lsmHarness;
-    protected boolean foundNext;
-    protected final ILSMIndexOperationContext opCtx;
-
-    protected List<ILSMComponent> operationalComponents;
-
-    public LSMRTreeAbstractCursor(ILSMIndexOperationContext opCtx) {
-        super();
-        this.opCtx = opCtx;
-    }
-
-    public RTreeSearchCursor getCursor(int cursorIndex) {
-        return rtreeCursors[cursorIndex];
-    }
-
-    @Override
-    public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException {
-        LSMRTreeCursorInitialState lsmInitialState = (LSMRTreeCursorInitialState) initialState;
-        btreeCmp = lsmInitialState.getBTreeCmp();
-        includeMemRTree = lsmInitialState.getIncludeMemComponent();
-        operationalComponents = lsmInitialState.getOperationalComponents();
-        lsmHarness = lsmInitialState.getLSMHarness();
-        numberOfTrees = lsmInitialState.getNumberOfTrees();
-        rTreeAccessors = lsmInitialState.getRTreeAccessors();
-        bTreeAccessors = lsmInitialState.getBTreeAccessors();
-
-        rtreeCursors = new RTreeSearchCursor[numberOfTrees];
-        btreeCursors = new ITreeIndexCursor[numberOfTrees];
-
-        int i = 0;
-        if (includeMemRTree) {
-            rtreeCursors[i] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
-                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
-                    .getRTreeLeafFrameFactory().createFrame());
-
-            // No need for a bloom filter for the in-memory BTree.
-            btreeCursors[i] = new BTreeRangeSearchCursor((IBTreeLeafFrame) lsmInitialState.getBTreeLeafFrameFactory()
-                    .createFrame(), false);
-            ++i;
-        }
-        for (; i < numberOfTrees; i++) {
-            rtreeCursors[i] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
-                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
-                    .getRTreeLeafFrameFactory().createFrame());
-
-            btreeCursors[i] = new BloomFilterAwareBTreePointSearchCursor((IBTreeLeafFrame) lsmInitialState
-                    .getBTreeLeafFrameFactory().createFrame(), false,
-                    ((LSMRTreeImmutableComponent) operationalComponents.get(i)).getBloomFilter());
-        }
-
-        rtreeSearchPredicate = (SearchPredicate) searchPred;
-        btreeRangePredicate = new RangePredicate(null, null, true, true, btreeCmp, btreeCmp);
-
-        open = true;
-    }
-
-    @Override
-    public ICachedPage getPage() {
-        // do nothing
-        return null;
-    }
-
-    @Override
-    public void close() throws HyracksDataException {
-        if (!open) {
-            return;
-        }
-
-        try {
-            if (rtreeCursors != null && btreeCursors != null) {
-                for (int i = 0; i < numberOfTrees; i++) {
-                    rtreeCursors[i].close();
-                    btreeCursors[i].close();
-                }
-            }
-            rtreeCursors = null;
-            btreeCursors = null;
-        } finally {
-            lsmHarness.endSearch(opCtx);
-        }
-
-        open = false;
-    }
-
-    @Override
-    public void setBufferCache(IBufferCache bufferCache) {
-        // do nothing
-    }
-
-    @Override
-    public void setFileId(int fileId) {
-        // do nothing
-    }
-
-    @Override
-    public ITupleReference getTuple() {
-        return frameTuple;
-    }
-
-    @Override
-    public boolean exclusiveLatchNodes() {
-        return false;
-    }
-
+package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
+import edu.uci.ics.hyracks.storage.am.btree.api.IBTreeLeafFrame;
+import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
+import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeRangeSearchCursor;
+import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
+import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
+import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
+import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
+import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
+import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent.LSMComponentType;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMHarness;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.BloomFilterAwareBTreePointSearchCursor;
+import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeInteriorFrame;
+import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeLeafFrame;
+import edu.uci.ics.hyracks.storage.am.rtree.impls.RTree;
+import edu.uci.ics.hyracks.storage.am.rtree.impls.RTreeSearchCursor;
+import edu.uci.ics.hyracks.storage.am.rtree.impls.SearchPredicate;
+import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
+import edu.uci.ics.hyracks.storage.common.buffercache.ICachedPage;
+
+public abstract class LSMRTreeAbstractCursor implements ITreeIndexCursor {
+
+    protected boolean open;
+    protected RTreeSearchCursor[] rtreeCursors;
+    protected ITreeIndexCursor[] btreeCursors;
+    protected ITreeIndexAccessor[] rtreeAccessors;
+    protected ITreeIndexAccessor[] btreeAccessors;
+    private MultiComparator btreeCmp;
+    protected int numberOfTrees;
+    protected SearchPredicate rtreeSearchPredicate;
+    protected RangePredicate btreeRangePredicate;
+    protected ITupleReference frameTuple;
+    protected boolean includeMutableComponent;
+    protected ILSMHarness lsmHarness;
+    protected boolean foundNext;
+    protected final ILSMIndexOperationContext opCtx;
+
+    protected List<ILSMComponent> operationalComponents;
+
+    public LSMRTreeAbstractCursor(ILSMIndexOperationContext opCtx) {
+        super();
+        this.opCtx = opCtx;
+    }
+
+    public RTreeSearchCursor getCursor(int cursorIndex) {
+        return rtreeCursors[cursorIndex];
+    }
+
+    @Override
+    public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException {
+        LSMRTreeCursorInitialState lsmInitialState = (LSMRTreeCursorInitialState) initialState;
+        btreeCmp = lsmInitialState.getBTreeCmp();
+
+        operationalComponents = lsmInitialState.getOperationalComponents();
+        lsmHarness = lsmInitialState.getLSMHarness();
+        numberOfTrees = operationalComponents.size();
+
+        rtreeCursors = new RTreeSearchCursor[numberOfTrees];
+        btreeCursors = new ITreeIndexCursor[numberOfTrees];
+        rtreeAccessors = new ITreeIndexAccessor[numberOfTrees];
+        btreeAccessors = new ITreeIndexAccessor[numberOfTrees];
+
+        includeMutableComponent = false;
+        for (int i = 0; i < numberOfTrees; i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            RTree rtree;
+            BTree btree;
+            if (component.getType() == LSMComponentType.MEMORY) {
+                includeMutableComponent = true;
+                // No need for a bloom filter for the in-memory BTree.
+                btreeCursors[i] = new BTreeRangeSearchCursor((IBTreeLeafFrame) lsmInitialState
+                        .getBTreeLeafFrameFactory().createFrame(), false);
+                rtree = (RTree) ((LSMRTreeMutableComponent) component).getRTree();
+                btree = (BTree) ((LSMRTreeMutableComponent) component).getBTree();
+            } else {
+                btreeCursors[i] = new BloomFilterAwareBTreePointSearchCursor((IBTreeLeafFrame) lsmInitialState
+                        .getBTreeLeafFrameFactory().createFrame(), false,
+                        ((LSMRTreeImmutableComponent) operationalComponents.get(i)).getBloomFilter());
+                rtree = (RTree) ((LSMRTreeImmutableComponent) component).getRTree();
+                btree = (BTree) ((LSMRTreeImmutableComponent) component).getBTree();
+            }
+            rtreeCursors[i] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
+                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
+                    .getRTreeLeafFrameFactory().createFrame());
+            rtreeAccessors[i] = rtree.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            btreeAccessors[i] = btree.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+        }
+
+        rtreeSearchPredicate = (SearchPredicate) searchPred;
+        btreeRangePredicate = new RangePredicate(null, null, true, true, btreeCmp, btreeCmp);
+
+        open = true;
+    }
+
+    @Override
+    public ICachedPage getPage() {
+        // do nothing
+        return null;
+    }
+
+    @Override
+    public void close() throws HyracksDataException {
+        if (!open) {
+            return;
+        }
+
+        try {
+            if (rtreeCursors != null && btreeCursors != null) {
+                for (int i = 0; i < numberOfTrees; i++) {
+                    rtreeCursors[i].close();
+                    btreeCursors[i].close();
+                }
+            }
+            rtreeCursors = null;
+            btreeCursors = null;
+        } finally {
+            lsmHarness.endSearch(opCtx);
+        }
+
+        open = false;
+    }
+
+    @Override
+    public void setBufferCache(IBufferCache bufferCache) {
+        // do nothing
+    }
+
+    @Override
+    public void setFileId(int fileId) {
+        // do nothing
+    }
+
+    @Override
+    public ITupleReference getTuple() {
+        return frameTuple;
+    }
+
+    @Override
+    public boolean exclusiveLatchNodes() {
+        return false;
+    }
+
 }
\ No newline at end of file
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeCursorInitialState.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeCursorInitialState.java
index 21230b0..27545b91 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeCursorInitialState.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeCursorInitialState.java
@@ -20,7 +20,6 @@
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
-import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrameFactory;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
@@ -29,35 +28,26 @@
 
 public class LSMRTreeCursorInitialState implements ICursorInitialState {
 
-    private final int numberOfTrees;
     private final ITreeIndexFrameFactory rtreeInteriorFrameFactory;
     private final ITreeIndexFrameFactory rtreeLeafFrameFactory;
     private final ITreeIndexFrameFactory btreeLeafFrameFactory;
     private final MultiComparator btreeCmp;
     private final MultiComparator hilbertCmp;
-    private final ITreeIndexAccessor[] rTreeAccessors;
-    private final ITreeIndexAccessor[] bTreeAccessors;
-    private final boolean includeMemRTree;
     private final ILSMHarness lsmHarness;
     private final int[] comparatorFields;
 
     private ISearchOperationCallback searchCallback;
     private final List<ILSMComponent> operationalComponents;
 
-    public LSMRTreeCursorInitialState(int numberOfTrees, ITreeIndexFrameFactory rtreeLeafFrameFactory,
+    public LSMRTreeCursorInitialState(ITreeIndexFrameFactory rtreeLeafFrameFactory,
             ITreeIndexFrameFactory rtreeInteriorFrameFactory, ITreeIndexFrameFactory btreeLeafFrameFactory,
-            MultiComparator btreeCmp, ITreeIndexAccessor[] rTreeAccessors, ITreeIndexAccessor[] bTreeAccessors,
-            boolean includeMemRTree, ILSMHarness lsmHarness, int[] comparatorFields,
+            MultiComparator btreeCmp, ILSMHarness lsmHarness, int[] comparatorFields,
             IBinaryComparatorFactory[] linearizerArray, ISearchOperationCallback searchCallback,
             List<ILSMComponent> operationalComponents) {
-        this.numberOfTrees = numberOfTrees;
         this.rtreeLeafFrameFactory = rtreeLeafFrameFactory;
         this.rtreeInteriorFrameFactory = rtreeInteriorFrameFactory;
         this.btreeLeafFrameFactory = btreeLeafFrameFactory;
         this.btreeCmp = btreeCmp;
-        this.rTreeAccessors = rTreeAccessors;
-        this.bTreeAccessors = bTreeAccessors;
-        this.includeMemRTree = includeMemRTree;
         this.lsmHarness = lsmHarness;
         this.comparatorFields = comparatorFields;
         this.hilbertCmp = MultiComparator.create(linearizerArray);
@@ -73,10 +63,6 @@
         return comparatorFields;
     }
 
-    public int getNumberOfTrees() {
-        return numberOfTrees;
-    }
-
     public ITreeIndexFrameFactory getRTreeInteriorFrameFactory() {
         return rtreeInteriorFrameFactory;
     }
@@ -106,18 +92,6 @@
         return operationalComponents;
     }
 
-    public ITreeIndexAccessor[] getRTreeAccessors() {
-        return rTreeAccessors;
-    }
-
-    public ITreeIndexAccessor[] getBTreeAccessors() {
-        return bTreeAccessors;
-    }
-
-    public boolean getIncludeMemComponent() {
-        return includeMemRTree;
-    }
-
     public ILSMHarness getLSMHarness() {
         return lsmHarness;
     }
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMutableComponent.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMutableComponent.java
index ffe583c..e960ee0 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMutableComponent.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMutableComponent.java
@@ -26,8 +26,8 @@
     private final RTree rtree;
     private final BTree btree;
 
-    public LSMRTreeMutableComponent(RTree rtree, BTree btree, IVirtualBufferCache vbc) {
-        super(vbc);
+    public LSMRTreeMutableComponent(RTree rtree, BTree btree, IVirtualBufferCache vbc, boolean isActive) {
+        super(vbc, isActive);
         this.rtree = rtree;
         this.btree = btree;
     }
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeOpContext.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeOpContext.java
index 8607a05..28b1572 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeOpContext.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeOpContext.java
@@ -24,7 +24,6 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrameFactory;
-import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexMetaDataFrame;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
@@ -37,43 +36,68 @@
 
 public final class LSMRTreeOpContext implements ILSMIndexOperationContext {
 
-    public RTreeOpContext rtreeOpContext;
-    public BTreeOpContext btreeOpContext;
-    public final RTree.RTreeAccessor memRTreeAccessor;
-    public final BTree.BTreeAccessor memBTreeAccessor;
+    public RTree.RTreeAccessor[] mutableRTreeAccessors;
+    public RTree.RTreeAccessor currentMutableRTreeAccessor;
+    public BTree.BTreeAccessor[] mutableBTreeAccessors;
+    public BTree.BTreeAccessor currentMutableBTreeAccessor;
+
+    public RTreeOpContext[] rtreeOpContexts;
+    public BTreeOpContext[] btreeOpContexts;
+    public RTreeOpContext currentRTreeOpContext;
+    public BTreeOpContext currentBTreeOpContext;
+
     private IndexOperation op;
     public final List<ILSMComponent> componentHolder;
     public final IModificationOperationCallback modificationCallback;
     public final ISearchOperationCallback searchCallback;
 
-    public LSMRTreeOpContext(RTree.RTreeAccessor memRtreeAccessor, IRTreeLeafFrame rtreeLeafFrame,
-            IRTreeInteriorFrame rtreeInteriorFrame, ITreeIndexMetaDataFrame rtreeMetaFrame, int rTreeHeightHint,
-            BTree.BTreeAccessor memBtreeAccessor, ITreeIndexFrameFactory btreeLeafFrameFactory,
-            ITreeIndexFrameFactory btreeInteriorFrameFactory, ITreeIndexMetaDataFrame btreeMetaFrame,
-            IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
-            IModificationOperationCallback modificationCallback, ISearchOperationCallback searchCallback) {
-        this.memRTreeAccessor = memRtreeAccessor;
-        this.memBTreeAccessor = memBtreeAccessor;
+    public LSMRTreeOpContext(List<LSMRTreeMutableComponent> mutableComponents, IRTreeLeafFrame rtreeLeafFrame,
+            IRTreeInteriorFrame rtreeInteriorFrame, ITreeIndexFrameFactory btreeLeafFrameFactory,
+            ITreeIndexFrameFactory btreeInteriorFrameFactory, IBinaryComparatorFactory[] rtreeCmpFactories,
+            IBinaryComparatorFactory[] btreeCmpFactories, IModificationOperationCallback modificationCallback,
+            ISearchOperationCallback searchCallback) {
+        mutableRTreeAccessors = new RTree.RTreeAccessor[mutableComponents.size()];
+        mutableBTreeAccessors = new BTree.BTreeAccessor[mutableComponents.size()];
+        rtreeOpContexts = new RTreeOpContext[mutableComponents.size()];
+        btreeOpContexts = new BTreeOpContext[mutableComponents.size()];
+
+        for (int i = 0; i < mutableComponents.size(); i++) {
+            mutableRTreeAccessors[i] = (RTree.RTreeAccessor) mutableComponents.get(i).getRTree()
+                    .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            mutableBTreeAccessors[i] = (BTree.BTreeAccessor) mutableComponents.get(i).getBTree()
+                    .createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+
+            rtreeOpContexts[i] = mutableRTreeAccessors[i].getOpContext();
+            btreeOpContexts[i] = mutableBTreeAccessors[i].getOpContext();
+        }
+
+        assert mutableComponents.size() > 0;
+        currentRTreeOpContext = rtreeOpContexts[0];
+        currentBTreeOpContext = btreeOpContexts[0];
         this.componentHolder = new LinkedList<ILSMComponent>();
         this.modificationCallback = modificationCallback;
         this.searchCallback = searchCallback;
-        this.rtreeOpContext = new RTreeOpContext(rtreeLeafFrame, rtreeInteriorFrame, rtreeMetaFrame, rtreeCmpFactories,
-                rTreeHeightHint, NoOpOperationCallback.INSTANCE);
-        this.btreeOpContext = new BTreeOpContext(memBtreeAccessor, btreeLeafFrameFactory, btreeInteriorFrameFactory,
-                btreeMetaFrame, btreeCmpFactories, NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
     }
 
     public void setOperation(IndexOperation newOp) {
         reset();
-        if (newOp == IndexOperation.INSERT) {
-            rtreeOpContext.setOperation(newOp);
-        } else if (newOp == IndexOperation.DELETE) {
-            btreeOpContext.setOperation(IndexOperation.INSERT);
-        }
         this.op = newOp;
     }
 
     @Override
+    public void setCurrentMutableComponentId(int currentMutableComponentId) {
+        currentMutableRTreeAccessor = mutableRTreeAccessors[currentMutableComponentId];
+        currentMutableBTreeAccessor = mutableBTreeAccessors[currentMutableComponentId];
+        currentRTreeOpContext = rtreeOpContexts[currentMutableComponentId];
+        currentBTreeOpContext = btreeOpContexts[currentMutableComponentId];
+        if (op == IndexOperation.INSERT) {
+            currentRTreeOpContext.setOperation(op);
+        } else if (op == IndexOperation.DELETE) {
+            currentBTreeOpContext.setOperation(IndexOperation.INSERT);
+        }
+    }
+
+    @Override
     public void reset() {
         componentHolder.clear();
     }
@@ -84,7 +108,7 @@
     }
 
     public MultiComparator getBTreeMultiComparator() {
-        return btreeOpContext.cmp;
+        return currentBTreeOpContext.cmp;
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSearchCursor.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSearchCursor.java
index 9b0869c..30dd467 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSearchCursor.java
@@ -61,7 +61,7 @@
         if (currentCursor < numberOfTrees) {
             rtreeCursors[currentCursor].reset();
             try {
-                rTreeAccessors[currentCursor].search(rtreeCursors[currentCursor], rtreeSearchPredicate);
+                rtreeAccessors[currentCursor].search(rtreeCursors[currentCursor], rtreeSearchPredicate);
             } catch (IndexException e) {
                 throw new HyracksDataException(e);
             }
@@ -80,14 +80,10 @@
 
                 boolean killerTupleFound = false;
                 for (int i = 0; i <= currentCursor; i++) {
-                    try {
-                        btreeCursors[i].reset();
-                        btreeRangePredicate.setHighKey(currentTuple, true);
-                        btreeRangePredicate.setLowKey(currentTuple, true);
-                        bTreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
-                    } catch (IndexException e) {
-                        throw new HyracksDataException(e);
-                    }
+                    btreeCursors[i].reset();
+                    btreeRangePredicate.setHighKey(currentTuple, true);
+                    btreeRangePredicate.setLowKey(currentTuple, true);
+                    btreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
                     try {
                         if (btreeCursors[i].hasNext()) {
                             killerTupleFound = true;
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSortedCursor.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSortedCursor.java
index 31dfe27..b93eb1b 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSortedCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeSortedCursor.java
@@ -44,7 +44,7 @@
             for (int i = 0; i < numberOfTrees; i++) {
                 rtreeCursors[i].reset();
                 try {
-                    rTreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
+                    rtreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
                 } catch (IndexException e) {
                     throw new HyracksDataException(e);
                 }
@@ -103,7 +103,7 @@
                     btreeCursors[i].reset();
                     btreeRangePredicate.setHighKey(frameTuple, true);
                     btreeRangePredicate.setLowKey(frameTuple, true);
-                    bTreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
+                    btreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
                 } catch (IndexException e) {
                     throw new HyracksDataException(e);
                 }
@@ -138,7 +138,7 @@
         for (int i = 0; i < numberOfTrees; i++) {
             rtreeCursors[i].reset();
             try {
-                rTreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
+                rtreeAccessors[i].search(rtreeCursors[i], rtreeSearchPredicate);
             } catch (IndexException e) {
                 throw new HyracksDataException(e);
             }
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
index 0be497a..6ccd681 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
@@ -16,7 +16,6 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
 
 import java.util.List;
-import java.util.ListIterator;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
@@ -25,7 +24,6 @@
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeRangeSearchCursor;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexBulkLoader;
-import edu.uci.ics.hyracks.storage.am.common.api.IIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
@@ -50,6 +48,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractMutableLSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMTreeIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.TreeIndexFactory;
@@ -67,7 +66,7 @@
     // because it should have a different tuple writer in it's leaf frames.
     private final ILSMComponentFactory bulkLoaComponentFactory;
 
-    public LSMRTreeWithAntiMatterTuples(IVirtualBufferCache virtualBufferCache,
+    public LSMRTreeWithAntiMatterTuples(List<IVirtualBufferCache> virtualBufferCaches,
             ITreeIndexFrameFactory rtreeInteriorFrameFactory, ITreeIndexFrameFactory rtreeLeafFrameFactory,
             ITreeIndexFrameFactory btreeInteriorFrameFactory, ITreeIndexFrameFactory btreeLeafFrameFactory,
             ILSMIndexFileManager fileManager, TreeIndexFactory<RTree> diskRTreeFactory,
@@ -76,7 +75,7 @@
             ILinearizeComparatorFactory linearizer, int[] comparatorFields, IBinaryComparatorFactory[] linearizerArray,
             ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
             ILSMIOOperationCallbackProvider ioOpCallbackProvider) {
-        super(virtualBufferCache, rtreeInteriorFrameFactory, rtreeLeafFrameFactory, btreeInteriorFrameFactory,
+        super(virtualBufferCaches, rtreeInteriorFrameFactory, rtreeLeafFrameFactory, btreeInteriorFrameFactory,
                 btreeLeafFrameFactory, fileManager, diskRTreeFactory, new LSMRTreeWithAntiMatterTuplesComponentFactory(
                         diskRTreeFactory), diskFileMapProvider, fieldCount, rtreeCmpFactories, btreeCmpFactories,
                 linearizer, comparatorFields, linearizerArray, 0, mergePolicy, opTracker, ioScheduler,
@@ -149,59 +148,14 @@
     }
 
     @Override
-    public void search(ILSMIndexOperationContext ictx, IIndexCursor cursor, ISearchPredicate pred)
-            throws HyracksDataException, IndexException {
-        LSMRTreeOpContext ctx = (LSMRTreeOpContext) ictx;
-        List<ILSMComponent> operationalComponents = ictx.getComponentHolder();
-        boolean includeMutableComponent = operationalComponents.get(0) == mutableComponent;
-        LSMRTreeWithAntiMatterTuplesSearchCursor lsmTreeCursor = (LSMRTreeWithAntiMatterTuplesSearchCursor) cursor;
-        int numDiskRComponents = operationalComponents.size();
-
-        LSMRTreeCursorInitialState initialState;
-        ITreeIndexAccessor[] bTreeAccessors = null;
-        if (includeMutableComponent) {
-            // Only in-memory BTree
-            bTreeAccessors = new ITreeIndexAccessor[1];
-            bTreeAccessors[0] = ctx.memBTreeAccessor;
-        }
-
-        initialState = new LSMRTreeCursorInitialState(numDiskRComponents, rtreeLeafFrameFactory,
-                rtreeInteriorFrameFactory, btreeLeafFrameFactory, ctx.getBTreeMultiComparator(), null, bTreeAccessors,
-                includeMutableComponent, lsmHarness, comparatorFields, linearizerArray, ctx.searchCallback,
-                operationalComponents);
-
-        lsmTreeCursor.open(initialState, pred);
-
-        ListIterator<ILSMComponent> diskComponentsIter = operationalComponents.listIterator();
-        int diskComponentIx = 0;
-        if (includeMutableComponent) {
-            // Open cursor of in-memory RTree
-            ctx.memRTreeAccessor.search(lsmTreeCursor.getMemRTreeCursor(), pred);
-            diskComponentIx++;
-            diskComponentsIter.next();
-        }
-
-        // Open cursors of on-disk RTrees.
-        ITreeIndexAccessor[] diskRTreeAccessors = new ITreeIndexAccessor[numDiskRComponents];
-        while (diskComponentsIter.hasNext()) {
-            RTree diskRTree = (RTree) ((LSMRTreeImmutableComponent) diskComponentsIter.next()).getRTree();
-            diskRTreeAccessors[diskComponentIx] = diskRTree.createAccessor(NoOpOperationCallback.INSTANCE,
-                    NoOpOperationCallback.INSTANCE);
-            diskRTreeAccessors[diskComponentIx].search(lsmTreeCursor.getCursor(diskComponentIx), pred);
-            diskComponentIx++;
-        }
-        lsmTreeCursor.initPriorityQueue();
-    }
-
-    @Override
     public boolean scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        if (!mutableComponent.isModified()) {
+        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
+        if (!((AbstractMutableLSMComponent) flushingComponent).isModified()) {
             return false;
         }
         LSMRTreeOpContext opCtx = createOpContext(NoOpOperationCallback.INSTANCE);
         LSMComponentFileReferences relFlushFileRefs = fileManager.getRelFlushFileReference();
-        ILSMComponent flushingComponent = ctx.getComponentHolder().get(0);
         opCtx.setOperation(IndexOperation.FLUSH);
         opCtx.getComponentHolder().add(flushingComponent);
         ILSMIndexAccessorInternal accessor = new LSMRTreeWithAntiMatterTuplesAccessor(lsmHarness, opCtx);
@@ -358,7 +312,7 @@
 
         public MultiComparator getMultiComparator() {
             LSMRTreeOpContext concreteCtx = (LSMRTreeOpContext) ctx;
-            return concreteCtx.rtreeOpContext.cmp;
+            return concreteCtx.currentRTreeOpContext.cmp;
         }
     }
 
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuplesSearchCursor.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuplesSearchCursor.java
index c937709..fbf0445 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuplesSearchCursor.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuplesSearchCursor.java
@@ -18,6 +18,7 @@
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.api.IBTreeLeafFrame;
+import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeRangeSearchCursor;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
@@ -25,74 +26,133 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent.LSMComponentType;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMIndexSearchCursor;
 import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeInteriorFrame;
 import edu.uci.ics.hyracks.storage.am.rtree.api.IRTreeLeafFrame;
+import edu.uci.ics.hyracks.storage.am.rtree.impls.RTree;
 import edu.uci.ics.hyracks.storage.am.rtree.impls.RTreeSearchCursor;
+import edu.uci.ics.hyracks.storage.am.rtree.impls.SearchPredicate;
 
 public class LSMRTreeWithAntiMatterTuplesSearchCursor extends LSMIndexSearchCursor {
 
-    private RTreeSearchCursor memRTreeCursor;
-    private BTreeRangeSearchCursor memBTreeCursor;
+    private ITreeIndexAccessor[] mutableRTreeAccessors;
+    private ITreeIndexAccessor[] btreeAccessors;
+    private RTreeSearchCursor[] mutableRTreeCursors;
+    private ITreeIndexCursor[] btreeCursors;
     private RangePredicate btreeRangePredicate;
-    private ITreeIndexAccessor memBTreeAccessor;
     private boolean foundNext;
     private ITupleReference frameTuple;
     private int[] comparatorFields;
     private MultiComparator btreeCmp;
+    private int currentCursor;
+    private SearchPredicate rtreeSearchPredicate;
+    private int numMutableComponents;
 
     public LSMRTreeWithAntiMatterTuplesSearchCursor(ILSMIndexOperationContext opCtx) {
         super(opCtx);
+        currentCursor = 0;
     }
 
     @Override
-    public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException {
+    public void open(ICursorInitialState initialState, ISearchPredicate searchPred) throws HyracksDataException,
+            IndexException {
         LSMRTreeCursorInitialState lsmInitialState = (LSMRTreeCursorInitialState) initialState;
         cmp = lsmInitialState.getHilbertCmp();
         btreeCmp = lsmInitialState.getBTreeCmp();
-        int numDiskRTrees = lsmInitialState.getNumberOfTrees();
-        rangeCursors = new RTreeSearchCursor[numDiskRTrees];
-        for (int i = 0; i < numDiskRTrees; i++) {
-            rangeCursors[i] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
-                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
-                    .getRTreeLeafFrameFactory().createFrame());
-        }
-        includeMemComponent = lsmInitialState.getIncludeMemComponent();
-        operationalComponents = lsmInitialState.getOperationalComponents();
-        if (includeMemComponent) {
-            memRTreeCursor = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState.getRTreeInteriorFrameFactory()
-                    .createFrame(), (IRTreeLeafFrame) lsmInitialState.getRTreeLeafFrameFactory().createFrame());
-            memBTreeCursor = new BTreeRangeSearchCursor((IBTreeLeafFrame) lsmInitialState.getBTreeLeafFrameFactory()
-                    .createFrame(), false);
-            memBTreeAccessor = lsmInitialState.getBTreeAccessors()[0];
-            btreeRangePredicate = new RangePredicate(null, null, true, true, btreeCmp, btreeCmp);
-        }
         lsmHarness = lsmInitialState.getLSMHarness();
         comparatorFields = lsmInitialState.getComparatorFields();
+        operationalComponents = lsmInitialState.getOperationalComponents();
+        rtreeSearchPredicate = (SearchPredicate) searchPred;
+
+        includeMutableComponent = false;
+        numMutableComponents = 0;
+        int numImmutableComponents = 0;
+        for (ILSMComponent component : operationalComponents) {
+            if (component.getType() == LSMComponentType.MEMORY) {
+                includeMutableComponent = true;
+                numMutableComponents++;
+            } else {
+                numImmutableComponents++;
+            }
+        }
+        if (includeMutableComponent) {
+            btreeRangePredicate = new RangePredicate(null, null, true, true, btreeCmp, btreeCmp);
+        }
+
+        mutableRTreeCursors = new RTreeSearchCursor[numMutableComponents];
+        mutableRTreeAccessors = new ITreeIndexAccessor[numMutableComponents];
+        btreeCursors = new BTreeRangeSearchCursor[numMutableComponents];
+        btreeAccessors = new ITreeIndexAccessor[numMutableComponents];
+        for (int i = 0; i < numMutableComponents; i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            RTree rtree = (RTree) ((LSMRTreeMutableComponent) component).getRTree();
+            BTree btree = (BTree) ((LSMRTreeMutableComponent) component).getBTree();
+            mutableRTreeCursors[i] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
+                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
+                    .getRTreeLeafFrameFactory().createFrame());
+            btreeCursors[i] = new BTreeRangeSearchCursor((IBTreeLeafFrame) lsmInitialState.getBTreeLeafFrameFactory()
+                    .createFrame(), false);
+            btreeAccessors[i] = btree.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            mutableRTreeAccessors[i] = rtree.createAccessor(NoOpOperationCallback.INSTANCE,
+                    NoOpOperationCallback.INSTANCE);
+        }
+
+        rangeCursors = new RTreeSearchCursor[numImmutableComponents];
+        ITreeIndexAccessor[] immutableRTreeAccessors = new ITreeIndexAccessor[numImmutableComponents];
+        int j = 0;
+        for (int i = numMutableComponents; i < operationalComponents.size(); i++) {
+            ILSMComponent component = operationalComponents.get(i);
+            rangeCursors[j] = new RTreeSearchCursor((IRTreeInteriorFrame) lsmInitialState
+                    .getRTreeInteriorFrameFactory().createFrame(), (IRTreeLeafFrame) lsmInitialState
+                    .getRTreeLeafFrameFactory().createFrame());
+            RTree rtree = (RTree) ((LSMRTreeImmutableComponent) component).getRTree();
+            immutableRTreeAccessors[j] = rtree.createAccessor(NoOpOperationCallback.INSTANCE,
+                    NoOpOperationCallback.INSTANCE);
+            immutableRTreeAccessors[j].search(rangeCursors[j], searchPred);
+            j++;
+        }
+        searchNextCursor();
         setPriorityQueueComparator();
+        initPriorityQueue();
+    }
+
+    private void searchNextCursor() throws HyracksDataException, IndexException {
+        if (currentCursor < numMutableComponents) {
+            mutableRTreeCursors[currentCursor].reset();
+            mutableRTreeAccessors[currentCursor].search(mutableRTreeCursors[currentCursor], rtreeSearchPredicate);
+        }
     }
 
     @Override
     public boolean hasNext() throws HyracksDataException, IndexException {
-        if (includeMemComponent) {
+        if (includeMutableComponent) {
             if (foundNext) {
                 return true;
             }
-            while (memRTreeCursor.hasNext()) {
-                memRTreeCursor.next();
-                ITupleReference memRTreeTuple = memRTreeCursor.getTuple();
-                if (searchMemBTree(memRTreeTuple)) {
-                    foundNext = true;
-                    frameTuple = memRTreeTuple;
-                    return true;
+
+            while (currentCursor < numMutableComponents) {
+                while (mutableRTreeCursors[currentCursor].hasNext()) {
+                    mutableRTreeCursors[currentCursor].next();
+                    ITupleReference currentTuple = mutableRTreeCursors[currentCursor].getTuple();
+                    if (searchMemBTrees(currentTuple, currentCursor)) {
+                        foundNext = true;
+                        frameTuple = currentTuple;
+                        return true;
+                    }
                 }
+                mutableRTreeCursors[currentCursor].close();
+                currentCursor++;
+                searchNextCursor();
             }
             while (super.hasNext()) {
                 super.next();
                 ITupleReference diskRTreeTuple = super.getTuple();
-                if (searchMemBTree(diskRTreeTuple)) {
+                if (searchMemBTrees(diskRTreeTuple, numMutableComponents - 1)) {
                     foundNext = true;
                     frameTuple = diskRTreeTuple;
                     return true;
@@ -107,7 +167,7 @@
 
     @Override
     public void next() throws HyracksDataException {
-        if (includeMemComponent) {
+        if (includeMutableComponent) {
             foundNext = false;
         } else {
             super.next();
@@ -117,7 +177,7 @@
 
     @Override
     public ITupleReference getTuple() {
-        if (includeMemComponent) {
+        if (includeMutableComponent) {
             return frameTuple;
         } else {
             return super.getTuple();
@@ -127,48 +187,49 @@
 
     @Override
     public void reset() throws HyracksDataException, IndexException {
-        if (includeMemComponent) {
-            memRTreeCursor.reset();
-            memBTreeCursor.reset();
+        if (includeMutableComponent) {
+            for (int i = 0; i < numMutableComponents; i++) {
+                mutableRTreeCursors[i].reset();
+                btreeCursors[i].reset();
+            }
         }
+        currentCursor = 0;
         super.reset();
     }
 
     @Override
     public void close() throws HyracksDataException {
-        if (includeMemComponent) {
-            memRTreeCursor.close();
-            memBTreeCursor.close();
+        if (includeMutableComponent) {
+            for (int i = 0; i < numMutableComponents; i++) {
+                mutableRTreeCursors[i].close();
+                btreeCursors[i].close();
+            }
         }
+        currentCursor = 0;
         super.close();
     }
 
-    public ITreeIndexCursor getMemRTreeCursor() {
-        return memRTreeCursor;
-    }
-
     @Override
     protected int compare(MultiComparator cmp, ITupleReference tupleA, ITupleReference tupleB) {
         return cmp.selectiveFieldCompare(tupleA, tupleB, comparatorFields);
     }
 
-    private boolean searchMemBTree(ITupleReference tuple) throws HyracksDataException {
-        try {
+    private boolean searchMemBTrees(ITupleReference tuple, int lastBTreeToSearch) throws HyracksDataException,
+            IndexException {
+        for (int i = 0; i <= lastBTreeToSearch; i++) {
+            btreeCursors[i].reset();
             btreeRangePredicate.setHighKey(tuple, true);
             btreeRangePredicate.setLowKey(tuple, true);
-            memBTreeAccessor.search(memBTreeCursor, btreeRangePredicate);
-        } catch (IndexException e) {
-            throw new HyracksDataException(e);
-        }
-        try {
-            if (memBTreeCursor.hasNext()) {
-                return false;
-            } else {
-                return true;
+            btreeAccessors[i].search(btreeCursors[i], btreeRangePredicate);
+            try {
+                if (btreeCursors[i].hasNext()) {
+                    return false;
+                }
+            } finally {
+                btreeCursors[i].close();
             }
-        } finally {
-            memBTreeCursor.close();
         }
+        return true;
     }
 
     @Override
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/utils/LSMRTreeUtils.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/utils/LSMRTreeUtils.java
index 50e5d09..b16d2b6 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/utils/LSMRTreeUtils.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/utils/LSMRTreeUtils.java
@@ -15,6 +15,8 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.utils;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ILinearizeComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
@@ -58,7 +60,7 @@
 import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;
 
 public class LSMRTreeUtils {
-    public static LSMRTree createLSMTree(IVirtualBufferCache virtualBufferCache, FileReference file,
+    public static LSMRTree createLSMTree(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
@@ -99,7 +101,7 @@
 
         ILSMIndexFileManager fileNameManager = new LSMRTreeFileManager(diskFileMapProvider, file, diskRTreeFactory,
                 diskBTreeFactory);
-        LSMRTree lsmTree = new LSMRTree(virtualBufferCache, rtreeInteriorFrameFactory, rtreeLeafFrameFactory,
+        LSMRTree lsmTree = new LSMRTree(virtualBufferCaches, rtreeInteriorFrameFactory, rtreeLeafFrameFactory,
                 btreeInteriorFrameFactory, btreeLeafFrameFactory, fileNameManager, diskRTreeFactory, diskBTreeFactory,
                 bloomFilterFactory, bloomFilterFalsePositiveRate, diskFileMapProvider, typeTraits.length,
                 rtreeCmpFactories, btreeCmpFactories, linearizeCmpFactory, comparatorFields, linearizerArray,
@@ -108,7 +110,7 @@
     }
 
     public static LSMRTreeWithAntiMatterTuples createLSMTreeWithAntiMatterTuples(
-            IVirtualBufferCache virtualBufferCache, FileReference file, IBufferCache diskBufferCache,
+            List<IVirtualBufferCache> virtualBufferCaches, FileReference file, IBufferCache diskBufferCache,
             IFileMapProvider diskFileMapProvider, ITypeTraits[] typeTraits,
             IBinaryComparatorFactory[] rtreeCmpFactories, IBinaryComparatorFactory[] btreeCmpFactories,
             IPrimitiveValueProviderFactory[] valueProviderFactories, RTreePolicyType rtreePolicyType,
@@ -151,7 +153,7 @@
 
         ILSMIndexFileManager fileNameManager = new LSMRTreeWithAntiMatterTuplesFileManager(diskFileMapProvider, file,
                 diskRTreeFactory);
-        LSMRTreeWithAntiMatterTuples lsmTree = new LSMRTreeWithAntiMatterTuples(virtualBufferCache,
+        LSMRTreeWithAntiMatterTuples lsmTree = new LSMRTreeWithAntiMatterTuples(virtualBufferCaches,
                 rtreeInteriorFrameFactory, rtreeLeafFrameFactory, btreeInteriorFrameFactory, btreeLeafFrameFactory,
                 fileNameManager, diskRTreeFactory, bulkLoadRTreeFactory, diskFileMapProvider, typeTraits.length,
                 rtreeCmpFactories, btreeCmpFactories, linearizerCmpFactory, comparatorFields, linearizerArray,
diff --git a/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTree.java b/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTree.java
index 528c004..7bb3583 100644
--- a/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTree.java
+++ b/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTree.java
@@ -147,7 +147,7 @@
     private RTreeOpContext createOpContext(IModificationOperationCallback modificationCallback) {
         return new RTreeOpContext((IRTreeLeafFrame) leafFrameFactory.createFrame(),
                 (IRTreeInteriorFrame) interiorFrameFactory.createFrame(), freePageManager.getMetaDataFrameFactory()
-                        .createFrame(), cmpFactories, 8, modificationCallback);
+                        .createFrame(), cmpFactories, modificationCallback);
     }
 
     private void insert(ITupleReference tuple, IIndexOperationContext ictx) throws HyracksDataException,
diff --git a/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTreeOpContext.java b/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTreeOpContext.java
index da73f85..a9171c3 100644
--- a/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTreeOpContext.java
+++ b/hyracks/hyracks-storage-am-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/impls/RTreeOpContext.java
@@ -31,6 +31,7 @@
 
 public class RTreeOpContext implements IIndexOperationContext {
     private static final int INITIAL_TRAVERSE_LIST_SIZE = 100;
+    private static final int INITIAL_HEIGHT = 8;
     public final MultiComparator cmp;
     public final IRTreeInteriorFrame interiorFrame;
     public final IRTreeLeafFrame leafFrame;
@@ -51,20 +52,20 @@
     public final IModificationOperationCallback modificationCallback;
 
     public RTreeOpContext(IRTreeLeafFrame leafFrame, IRTreeInteriorFrame interiorFrame,
-            ITreeIndexMetaDataFrame metaFrame, IBinaryComparatorFactory[] cmpFactories, int treeHeightHint,
+            ITreeIndexMetaDataFrame metaFrame, IBinaryComparatorFactory[] cmpFactories,
             IModificationOperationCallback modificationCallback) {
-        
-        if (cmpFactories[0] != null) { 
+
+        if (cmpFactories[0] != null) {
             this.cmp = MultiComparator.create(cmpFactories);
         } else {
             this.cmp = null;
         }
-        
+
         this.interiorFrame = interiorFrame;
         this.leafFrame = leafFrame;
         this.metaFrame = metaFrame;
         this.modificationCallback = modificationCallback;
-        pathList = new PathList(treeHeightHint, treeHeightHint);
+        pathList = new PathList(INITIAL_HEIGHT, INITIAL_HEIGHT);
         NSNUpdates = new ArrayList<ICachedPage>();
         LSNUpdates = new ArrayList<ICachedPage>();
     }
diff --git a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/config/AccessMethodTestsConfig.java b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/config/AccessMethodTestsConfig.java
index 693dc47..52f1a9f 100644
--- a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/config/AccessMethodTestsConfig.java
+++ b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/config/AccessMethodTestsConfig.java
@@ -29,6 +29,7 @@
     public static final int LSM_RTREE_BULKLOAD_ROUNDS = 5;
     public static final int LSM_RTREE_MAX_TREES_TO_MERGE = 3;
     public static final boolean LSM_RTREE_TEST_RSTAR_POLICY = false;
+    public static final int LSM_RTREE_NUM_MUTABLE_COMPONENTS = 2;
 
     // Test params for BTree, LSMBTree.
     public static final int BTREE_NUM_TUPLES_TO_INSERT = 100;
@@ -39,17 +40,18 @@
     // Test params for LSMBTree only.
     public static final int LSM_BTREE_BULKLOAD_ROUNDS = 5;
     public static final int LSM_BTREE_MAX_TREES_TO_MERGE = 10;
+    public static final int LSM_BTREE_NUM_MUTABLE_COMPONENTS = 2;
 
     // Mem configuration for RTree.
     public static final int RTREE_PAGE_SIZE = 512;
     public static final int RTREE_NUM_PAGES = 1000;
-    public static final int RTREE_MAX_OPEN_FILES = 10;
+    public static final int RTREE_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int RTREE_HYRACKS_FRAME_SIZE = 128;
 
     // Mem configuration for LSMRTree and LSMRTreeWithAntiMatterTuples.
     public static final int LSM_RTREE_DISK_PAGE_SIZE = 512;
     public static final int LSM_RTREE_DISK_NUM_PAGES = 1000;
-    public static final int LSM_RTREE_DISK_MAX_OPEN_FILES = 2000;
+    public static final int LSM_RTREE_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int LSM_RTREE_MEM_PAGE_SIZE = 512;
     public static final int LSM_RTREE_MEM_NUM_PAGES = 1000;
     public static final int LSM_RTREE_HYRACKS_FRAME_SIZE = 128;
@@ -58,13 +60,13 @@
     // Mem configuration for BTree.
     public static final int BTREE_PAGE_SIZE = 256;
     public static final int BTREE_NUM_PAGES = 100;
-    public static final int BTREE_MAX_OPEN_FILES = 10;
+    public static final int BTREE_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int BTREE_HYRACKS_FRAME_SIZE = 128;
 
     // Mem configuration for LSMBTree.
     public static final int LSM_BTREE_DISK_PAGE_SIZE = 256;
     public static final int LSM_BTREE_DISK_NUM_PAGES = 1000;
-    public static final int LSM_BTREE_DISK_MAX_OPEN_FILES = 200;
+    public static final int LSM_BTREE_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int LSM_BTREE_MEM_PAGE_SIZE = 256;
     public static final int LSM_BTREE_MEM_NUM_PAGES = 100;
     public static final int LSM_BTREE_HYRACKS_FRAME_SIZE = 128;
@@ -73,11 +75,13 @@
     // Mem configuration for Inverted Index.
     public static final int LSM_INVINDEX_DISK_PAGE_SIZE = 1024;
     public static final int LSM_INVINDEX_DISK_NUM_PAGES = 1000;
-    public static final int LSM_INVINDEX_DISK_MAX_OPEN_FILES = 1000;
+    public static final int LSM_INVINDEX_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int LSM_INVINDEX_MEM_PAGE_SIZE = 1024;
     public static final int LSM_INVINDEX_MEM_NUM_PAGES = 100;
     public static final int LSM_INVINDEX_HYRACKS_FRAME_SIZE = 32768;
     public static final double LSM_INVINDEX_BLOOMFILTER_FALSE_POSITIVE_RATE = 0.01;
+    public static final int LSM_INVINDEX_NUM_MUTABLE_COMPONENTS = 2;
+
     // Test parameters.
     public static final int LSM_INVINDEX_NUM_DOCS_TO_INSERT = 100;
     // Used for full-fledged search test.
@@ -100,7 +104,7 @@
     // Mem configuration for BloomFilter.
     public static final int BLOOM_FILTER_PAGE_SIZE = 256;
     public static final int BLOOM_FILTER_NUM_PAGES = 1000;
-    public static final int BLOOM_FILTER_MAX_OPEN_FILES = 10;
+    public static final int BLOOM_FILTER_MAX_OPEN_FILES = Integer.MAX_VALUE;
     public static final int BLOOM_FILTER_HYRACKS_FRAME_SIZE = 128;
 
 }
@@ -129,13 +133,13 @@
 // Mem configuration for RTree.
 public static final int RTREE_PAGE_SIZE = 512;
 public static final int RTREE_NUM_PAGES = 1000;
-public static final int RTREE_MAX_OPEN_FILES = 10;
+public static final int RTREE_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int RTREE_HYRACKS_FRAME_SIZE = 128;
 	
 // Mem configuration for LSMRTree and LSMRTreeWithAntiMatterTuples.
 public static final int LSM_RTREE_DISK_PAGE_SIZE = 256;
 public static final int LSM_RTREE_DISK_NUM_PAGES = 1000;
-public static final int LSM_RTREE_DISK_MAX_OPEN_FILES = 2000;
+public static final int LSM_RTREE_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int LSM_RTREE_MEM_PAGE_SIZE = 256;
 public static final int LSM_RTREE_MEM_NUM_PAGES = 1000;
 public static final int LSM_RTREE_HYRACKS_FRAME_SIZE = 128;
@@ -143,13 +147,13 @@
 // Mem configuration for BTree.
 public static final int BTREE_PAGE_SIZE = 256;
 public static final int BTREE_NUM_PAGES = 100;
-public static final int BTREE_MAX_OPEN_FILES = 10;
+public static final int BTREE_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int BTREE_HYRACKS_FRAME_SIZE = 128;
 	
 // Mem configuration for LSMBTree.
 public static final int LSM_BTREE_DISK_PAGE_SIZE = 256;
 public static final int LSM_BTREE_DISK_NUM_PAGES = 1000;
-public static final int LSM_BTREE_DISK_MAX_OPEN_FILES = 200;
+public static final int LSM_BTREE_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int LSM_BTREE_MEM_PAGE_SIZE = 256;
 public static final int LSM_BTREE_MEM_NUM_PAGES = 100;
 public static final int LSM_BTREE_HYRACKS_FRAME_SIZE = 128;
@@ -157,13 +161,13 @@
 // Mem configuration for Inverted Index.
 public static final int INVINDEX_PAGE_SIZE = 32768;
 public static final int INVINDEX_NUM_PAGES = 100;
-public static final int INVINDEX_MAX_OPEN_FILES = 10;
+public static final int INVINDEX_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int INVINDEX_HYRACKS_FRAME_SIZE = 32768;
 
 // Mem configuration for Inverted Index.
 public static final int LSM_INVINDEX_DISK_PAGE_SIZE = 1024;
 public static final int LSM_INVINDEX_DISK_NUM_PAGES = 1000;
-public static final int LSM_INVINDEX_DISK_MAX_OPEN_FILES = 1000;
+public static final int LSM_INVINDEX_DISK_MAX_OPEN_FILES = Integer.MAX_VALUE;
 public static final int LSM_INVINDEX_MEM_PAGE_SIZE = 1024;
 public static final int LSM_INVINDEX_MEM_NUM_PAGES = 100;
 public static final int LSM_INVINDEX_HYRACKS_FRAME_SIZE = 32768;
diff --git a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/AbstractRTreeExamplesTest.java b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/AbstractRTreeExamplesTest.java
index 44ab0d9..705a976 100644
--- a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/AbstractRTreeExamplesTest.java
+++ b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/storage/am/rtree/AbstractRTreeExamplesTest.java
@@ -134,12 +134,6 @@
 
             TupleUtils.createIntegerTuple(tb, tuple, Math.min(p1x, p2x), Math.min(p1y, p2y), Math.max(p1x, p2x),
                     Math.max(p1y, p2y), pk1, pk2);
-            if (LOGGER.isLoggable(Level.INFO)) {
-                if (i % 1000 == 0) {
-                    LOGGER.info("Inserting " + i + " " + Math.min(p1x, p2x) + " " + Math.min(p1y, p2y) + " "
-                            + Math.max(p1x, p2x) + " " + Math.max(p1y, p2y) + ", " + pk1 + ", " + pk2);
-                }
-            }
             try {
                 indexAccessor.insert(tuple);
             } catch (TreeIndexException e) {
@@ -494,13 +488,6 @@
 
             TupleUtils.createDoubleTuple(tb, tuple, Math.min(p1x, p2x), Math.min(p1y, p2y), Math.min(p1z, p2z),
                     Math.max(p1x, p2x), Math.max(p1y, p2y), Math.max(p1z, p2z), pk);
-            if (LOGGER.isLoggable(Level.INFO)) {
-                if (i % 1000 == 0) {
-                    LOGGER.info("Inserting " + i + " " + Math.min(p1x, p2x) + " " + Math.min(p1y, p2y) + " "
-                            + Math.min(p1z, p2z) + " " + Math.max(p1x, p2x) + " " + Math.max(p1y, p2y) + " "
-                            + Math.max(p1z, p2z) + ", " + pk);
-                }
-            }
             try {
                 indexAccessor.insert(tuple);
             } catch (TreeIndexException e) {
@@ -608,11 +595,6 @@
 
                 TupleUtils.createIntegerTuple(tb, tuple, Math.min(p1x, p2x), Math.min(p1y, p2y), Math.max(p1x, p2x),
                         Math.max(p1y, p2y), pk);
-                if (LOGGER.isLoggable(Level.INFO)) {
-                    if (i % 1000 == 0) {
-                        LOGGER.info("Inserting " + i);
-                    }
-                }
                 try {
                     indexAccessor.insert(tuple);
                 } catch (TreeIndexException e) {
@@ -626,11 +608,6 @@
             int delDone = 0;
             for (int i = 0; i < numInserts; i++) {
                 TupleUtils.createIntegerTuple(tb, tuple, p1xs[i], p1ys[i], p2xs[i], p2ys[i], pks[i]);
-                if (LOGGER.isLoggable(Level.INFO)) {
-                    if (i % 1000 == 0) {
-                        LOGGER.info("Deleting " + i);
-                    }
-                }
                 try {
                     indexAccessor.delete(tuple);
                     delDone++;
diff --git a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/test/support/TestVirtualBufferCacheProvider.java b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/test/support/TestVirtualBufferCacheProvider.java
index 9db21cb..afbb86b 100644
--- a/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/test/support/TestVirtualBufferCacheProvider.java
+++ b/hyracks/hyracks-test-support/src/main/java/edu/uci/ics/hyracks/test/support/TestVirtualBufferCacheProvider.java
@@ -14,6 +14,9 @@
  */
 package edu.uci.ics.hyracks.test.support;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCacheProvider;
@@ -33,7 +36,12 @@
     }
 
     @Override
-    public IVirtualBufferCache getVirtualBufferCache(IHyracksTaskContext ctx) {
-        return new VirtualBufferCache(new HeapBufferAllocator(), pageSize, numPages);
+    public List<IVirtualBufferCache> getVirtualBufferCaches(IHyracksTaskContext ctx) {
+        List<IVirtualBufferCache> vbcs = new ArrayList<IVirtualBufferCache>();
+        for (int i = 0; i < 2; i++) {
+            IVirtualBufferCache vbc = new VirtualBufferCache(new HeapBufferAllocator(), pageSize, numPages / 2);
+            vbcs.add(vbc);
+        }
+        return vbcs;
     }
 }
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeBulkLoadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeBulkLoadTest.java
index e0a2a46..753be5d 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeBulkLoadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeBulkLoadTest.java
@@ -51,7 +51,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeDeleteTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeDeleteTest.java
index 122b788..646343a 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeDeleteTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeDeleteTest.java
@@ -51,7 +51,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeExamplesTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeExamplesTest.java
index 60e0492..b0617a1 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeExamplesTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeExamplesTest.java
@@ -34,7 +34,7 @@
     @Override
     protected ITreeIndex createTreeIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] cmpFactories,
             int[] bloomFilterKeyFields) throws TreeIndexException {
-        return LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits, cmpFactories,
                 bloomFilterKeyFields, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeInsertTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeInsertTest.java
index 76a0206..bce69a2 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeInsertTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeInsertTest.java
@@ -51,7 +51,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeLifecycleTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeLifecycleTest.java
index 639fd47..0f903e5 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeLifecycleTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeLifecycleTest.java
@@ -53,7 +53,7 @@
     @Override
     public void setup() throws Exception {
         harness.setUp();
-        testCtx = LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        testCtx = LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, fieldSerdes.length,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMergeTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMergeTest.java
index e3c86df..ab46f3f 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMergeTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMergeTest.java
@@ -50,7 +50,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
index 77b65ca..cc3389f 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
@@ -42,7 +42,7 @@
 
     @Override
     protected void createIndexInstance() throws Exception {
-        index = LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        index = LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 SerdeUtils.serdesToTypeTraits(keySerdes),
                 SerdeUtils.serdesToComparatorFactories(keySerdes, keySerdes.length), bloomFilterKeyFields,
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMultiBulkLoadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMultiBulkLoadTest.java
index a7c8b81..d7d29a8 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMultiBulkLoadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeMultiBulkLoadTest.java
@@ -52,7 +52,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeSearchOperationCallbackTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeSearchOperationCallbackTest.java
index e15e80a..ce9ae0e 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeSearchOperationCallbackTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeSearchOperationCallbackTest.java
@@ -49,7 +49,7 @@
 
     @Override
     protected void createIndexInstance() throws Exception {
-        index = LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        index = LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 SerdeUtils.serdesToTypeTraits(keySerdes),
                 SerdeUtils.serdesToComparatorFactories(keySerdes, keySerdes.length), bloomFilterKeyFields,
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeUpdateTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeUpdateTest.java
index db221a2..6f8ef84 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeUpdateTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/LSMBTreeUpdateTest.java
@@ -51,7 +51,7 @@
     @Override
     protected OrderedIndexTestContext createTestContext(ISerializerDeserializer[] fieldSerdes, int numKeys,
             BTreeLeafFrameType leafType) throws Exception {
-        return LSMBTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, numKeys,
                 harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(), harness.getOperationTracker(),
                 harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeMultiThreadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeMultiThreadTest.java
index 9dfa713..1ae201f 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeMultiThreadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeMultiThreadTest.java
@@ -50,7 +50,7 @@
     @Override
     protected ITreeIndex createIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] cmpFactories,
             int[] bloomFilterKeyFields) throws TreeIndexException {
-        return LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMBTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits, cmpFactories,
                 bloomFilterKeyFields, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/perf/LSMTreeRunner.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/perf/LSMTreeRunner.java
index fc6642c..3591f78a 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/perf/LSMTreeRunner.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/perf/LSMTreeRunner.java
@@ -17,7 +17,9 @@
 
 import java.io.File;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
@@ -88,10 +90,15 @@
         ioDeviceId = 0;
         IFileMapProvider fmp = TestStorageManagerComponentHolder.getFileMapProvider(ctx);
 
-        IVirtualBufferCache virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), inMemPageSize,
-                inMemNumPages);
+        List<IVirtualBufferCache> virtualBufferCaches = new ArrayList<IVirtualBufferCache>();
+        for (int i = 0; i < 2; i++) {
+            IVirtualBufferCache virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), inMemPageSize,
+                    inMemNumPages);
+            virtualBufferCaches.add(virtualBufferCache);
+        }
+
         this.ioScheduler = SynchronousScheduler.INSTANCE;
-        lsmtree = LSMBTreeUtils.createLSMTree(virtualBufferCache, file, bufferCache, fmp, typeTraits, cmpFactories,
+        lsmtree = LSMBTreeUtils.createLSMTree(virtualBufferCaches, file, bufferCache, fmp, typeTraits, cmpFactories,
                 bloomFilterKeyFields, bloomFilterFalsePositiveRate, NoMergePolicy.INSTANCE,
                 new ThreadCountingTracker(), ioScheduler, NoOpIOOperationCallback.INSTANCE);
     }
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestContext.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestContext.java
index ab78ee61..39e7184 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestContext.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestContext.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.btree.util;
 
 import java.util.Collection;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
@@ -62,7 +63,7 @@
         upsertCheckTuple(checkTuple, checkTuples);
     }
 
-    public static LSMBTreeTestContext create(IVirtualBufferCache virtualBufferCache, FileReference file,
+    public static LSMBTreeTestContext create(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ISerializerDeserializer[] fieldSerdes,
             int numKeyFields, double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy,
             ILSMOperationTracker opTracker, ILSMIOOperationScheduler ioScheduler,
@@ -73,7 +74,7 @@
         for (int i = 0; i < numKeyFields; ++i) {
             bloomFilterKeyFields[i] = i;
         }
-        LSMBTree lsmTree = LSMBTreeUtils.createLSMTree(virtualBufferCache, file, diskBufferCache, diskFileMapProvider,
+        LSMBTree lsmTree = LSMBTreeUtils.createLSMTree(virtualBufferCaches, file, diskBufferCache, diskFileMapProvider,
                 typeTraits, cmpFactories, bloomFilterKeyFields, bloomFilterFalsePositiveRate, mergePolicy, opTracker,
                 ioScheduler, ioOpCallbackProvider);
         LSMBTreeTestContext testCtx = new LSMBTreeTestContext(fieldSerdes, lsmTree);
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestHarness.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestHarness.java
index e643cf9..216861f 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestHarness.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/util/LSMBTreeTestHarness.java
@@ -18,7 +18,9 @@
 import java.io.File;
 import java.io.FilenameFilter;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 import java.util.Random;
 import java.util.logging.Logger;
 
@@ -60,12 +62,13 @@
     protected final int memNumPages;
     protected final int hyracksFrameSize;
     protected final double bloomFilterFalsePositiveRate;
+    protected final int numMutableComponents;
 
     protected IOManager ioManager;
     protected int ioDeviceId;
     protected IBufferCache diskBufferCache;
     protected IFileMapProvider diskFileMapProvider;
-    protected IVirtualBufferCache virtualBufferCache;
+    protected List<IVirtualBufferCache> virtualBufferCaches;
     protected IHyracksTaskContext ctx;
     protected ILSMIOOperationScheduler ioScheduler;
     protected ILSMMergePolicy mergePolicy;
@@ -90,20 +93,7 @@
         this.mergePolicy = NoMergePolicy.INSTANCE;
         this.opTracker = new ThreadCountingTracker();
         this.ioOpCallbackProvider = NoOpIOOperationCallback.INSTANCE;
-    }
-
-    public LSMBTreeTestHarness(int diskPageSize, int diskNumPages, int diskMaxOpenFiles, int memPageSize,
-            int memNumPages, int hyracksFrameSize, double bloomFilterFalsePositiveRate) {
-        this.diskPageSize = diskPageSize;
-        this.diskNumPages = diskNumPages;
-        this.diskMaxOpenFiles = diskMaxOpenFiles;
-        this.memPageSize = memPageSize;
-        this.memNumPages = memNumPages;
-        this.hyracksFrameSize = hyracksFrameSize;
-        this.bloomFilterFalsePositiveRate = bloomFilterFalsePositiveRate;
-        this.ioScheduler = SynchronousScheduler.INSTANCE;
-        this.mergePolicy = NoMergePolicy.INSTANCE;
-        this.opTracker = new ThreadCountingTracker();
+        this.numMutableComponents = AccessMethodTestsConfig.LSM_BTREE_NUM_MUTABLE_COMPONENTS;
     }
 
     public void setUp() throws HyracksException {
@@ -116,7 +106,12 @@
         TestStorageManagerComponentHolder.init(diskPageSize, diskNumPages, diskMaxOpenFiles);
         diskBufferCache = TestStorageManagerComponentHolder.getBufferCache(ctx);
         diskFileMapProvider = TestStorageManagerComponentHolder.getFileMapProvider(ctx);
-        virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), memPageSize, memNumPages);
+        virtualBufferCaches = new ArrayList<IVirtualBufferCache>();
+        for (int i = 0; i < numMutableComponents; i++) {
+            IVirtualBufferCache virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), memPageSize,
+                    memNumPages / numMutableComponents);
+            virtualBufferCaches.add(virtualBufferCache);
+        }
         rnd.setSeed(RANDOM_SEED);
     }
 
@@ -179,8 +174,8 @@
         return diskFileMapProvider;
     }
 
-    public IVirtualBufferCache getVirtualBufferCache() {
-        return virtualBufferCache;
+    public List<IVirtualBufferCache> getVirtualBufferCaches() {
+        return virtualBufferCaches;
     }
 
     public double getBoomFilterFalsePositiveRate() {
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/common/LSMInvertedIndexTestHarness.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/common/LSMInvertedIndexTestHarness.java
index 7276464..99087f0 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/common/LSMInvertedIndexTestHarness.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/common/LSMInvertedIndexTestHarness.java
@@ -18,7 +18,9 @@
 import java.io.File;
 import java.io.FilenameFilter;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 import java.util.Random;
 
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
@@ -27,15 +29,12 @@
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.control.nc.io.IOManager;
-import edu.uci.ics.hyracks.storage.am.common.api.IVirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.config.AccessMethodTestsConfig;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallbackProvider;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
-import edu.uci.ics.hyracks.storage.am.lsm.common.freepage.VirtualFreePageManager;
-import edu.uci.ics.hyracks.storage.am.lsm.common.impls.MultitenantVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.NoMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.NoOpIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.SynchronousScheduler;
@@ -58,13 +57,13 @@
     protected final int memNumPages;
     protected final int hyracksFrameSize;
     protected final double bloomFilterFalsePositiveRate;
+    protected final int numMutableComponents;
 
     protected IOManager ioManager;
     protected int ioDeviceId;
     protected IBufferCache diskBufferCache;
     protected IFileMapProvider diskFileMapProvider;
-    protected IVirtualBufferCache virtualBufferCache;
-    protected IVirtualFreePageManager virtualFreePageManager;
+    protected List<IVirtualBufferCache> virtualBufferCaches;
     protected IHyracksTaskContext ctx;
     protected ILSMIOOperationScheduler ioScheduler;
     protected ILSMMergePolicy mergePolicy;
@@ -91,20 +90,7 @@
         this.mergePolicy = NoMergePolicy.INSTANCE;
         this.opTracker = new ThreadCountingTracker();
         this.ioOpCallbackProvider = NoOpIOOperationCallback.INSTANCE;
-    }
-
-    public LSMInvertedIndexTestHarness(int diskPageSize, int diskNumPages, int diskMaxOpenFiles, int memPageSize,
-            int memNumPages, int hyracksFrameSize, double bloomFilterFalsePositiveRate) {
-        this.diskPageSize = diskPageSize;
-        this.diskNumPages = diskNumPages;
-        this.diskMaxOpenFiles = diskMaxOpenFiles;
-        this.memPageSize = memPageSize;
-        this.memNumPages = memNumPages;
-        this.hyracksFrameSize = hyracksFrameSize;
-        this.bloomFilterFalsePositiveRate = bloomFilterFalsePositiveRate;
-        this.ioScheduler = SynchronousScheduler.INSTANCE;
-        this.mergePolicy = NoMergePolicy.INSTANCE;
-        this.opTracker = new ThreadCountingTracker();
+        this.numMutableComponents = AccessMethodTestsConfig.LSM_INVINDEX_NUM_MUTABLE_COMPONENTS;
     }
 
     public void setUp() throws HyracksException {
@@ -116,10 +102,12 @@
         TestStorageManagerComponentHolder.init(diskPageSize, diskNumPages, diskMaxOpenFiles);
         diskBufferCache = TestStorageManagerComponentHolder.getBufferCache(ctx);
         diskFileMapProvider = TestStorageManagerComponentHolder.getFileMapProvider(ctx);
-        virtualBufferCache = new MultitenantVirtualBufferCache(new VirtualBufferCache(new HeapBufferAllocator(),
-                memPageSize, memNumPages));
-        virtualBufferCache.open();
-        virtualFreePageManager = new VirtualFreePageManager(memNumPages);
+        virtualBufferCaches = new ArrayList<IVirtualBufferCache>();
+        for (int i = 0; i < numMutableComponents; i++) {
+            IVirtualBufferCache virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), memPageSize,
+                    memNumPages / numMutableComponents);
+            virtualBufferCaches.add(virtualBufferCache);
+        }
         rnd.setSeed(RANDOM_SEED);
         invIndexFileRef = ioManager.getIODevices().get(0).createFileReference(onDiskDir + invIndexFileName);
     }
@@ -141,7 +129,6 @@
             }
         }
         dir.delete();
-        virtualBufferCache.close();
     }
 
     public FileReference getInvListsFileRef() {
@@ -188,18 +175,14 @@
         return diskFileMapProvider;
     }
 
-    public IVirtualBufferCache getVirtualBufferCache() {
-        return virtualBufferCache;
+    public List<IVirtualBufferCache> getVirtualBufferCaches() {
+        return virtualBufferCaches;
     }
 
     public double getBoomFilterFalsePositiveRate() {
         return bloomFilterFalsePositiveRate;
     }
 
-    public IVirtualFreePageManager getVirtualFreePageManager() {
-        return virtualFreePageManager;
-    }
-
     public IHyracksTaskContext getHyracksTastContext() {
         return ctx;
     }
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/LSMInvertedIndexTestContext.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/LSMInvertedIndexTestContext.java
index 05dc1b5..5edf74e 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/LSMInvertedIndexTestContext.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/util/LSMInvertedIndexTestContext.java
@@ -36,6 +36,7 @@
 import edu.uci.ics.hyracks.storage.am.common.CheckTuple;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndex;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.lsm.common.freepage.VirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndex;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.common.LSMInvertedIndexTestHarness;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.exceptions.InvertedIndexException;
@@ -118,18 +119,20 @@
         }
         // Create index and test context.        
         IInvertedIndex invIndex;
+        assert harness.getVirtualBufferCaches().size() > 0;
         switch (invIndexType) {
             case INMEMORY: {
-                invIndex = InvertedIndexUtils.createInMemoryBTreeInvertedindex(harness.getVirtualBufferCache(),
-                        harness.getVirtualFreePageManager(), invListTypeTraits, invListCmpFactories, tokenTypeTraits,
-                        tokenCmpFactories, tokenizerFactory, new FileReference(new File(harness.getOnDiskDir())));
+                invIndex = InvertedIndexUtils.createInMemoryBTreeInvertedindex(harness.getVirtualBufferCaches().get(0),
+                        new VirtualFreePageManager(harness.getVirtualBufferCaches().get(0).getNumPages()),
+                        invListTypeTraits, invListCmpFactories, tokenTypeTraits, tokenCmpFactories, tokenizerFactory,
+                        new FileReference(new File(harness.getOnDiskDir())));
                 break;
             }
             case PARTITIONED_INMEMORY: {
                 invIndex = InvertedIndexUtils.createPartitionedInMemoryBTreeInvertedindex(harness
-                        .getVirtualBufferCache(), harness.getVirtualFreePageManager(), invListTypeTraits,
-                        invListCmpFactories, tokenTypeTraits, tokenCmpFactories, tokenizerFactory, new FileReference(
-                                new File(harness.getOnDiskDir())));
+                        .getVirtualBufferCaches().get(0), new VirtualFreePageManager(harness.getVirtualBufferCaches()
+                        .get(0).getNumPages()), invListTypeTraits, invListCmpFactories, tokenTypeTraits,
+                        tokenCmpFactories, tokenizerFactory, new FileReference(new File(harness.getOnDiskDir())));
                 break;
             }
             case ONDISK: {
@@ -145,7 +148,7 @@
                 break;
             }
             case LSM: {
-                invIndex = InvertedIndexUtils.createLSMInvertedIndex(harness.getVirtualBufferCache(),
+                invIndex = InvertedIndexUtils.createLSMInvertedIndex(harness.getVirtualBufferCaches(),
                         harness.getDiskFileMapProvider(), invListTypeTraits, invListCmpFactories, tokenTypeTraits,
                         tokenCmpFactories, tokenizerFactory, harness.getDiskBufferCache(), harness.getOnDiskDir(),
                         harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
@@ -154,7 +157,7 @@
                 break;
             }
             case PARTITIONED_LSM: {
-                invIndex = InvertedIndexUtils.createPartitionedLSMInvertedIndex(harness.getVirtualBufferCache(),
+                invIndex = InvertedIndexUtils.createPartitionedLSMInvertedIndex(harness.getVirtualBufferCaches(),
                         harness.getDiskFileMapProvider(), invListTypeTraits, invListCmpFactories, tokenTypeTraits,
                         tokenCmpFactories, tokenizerFactory, harness.getDiskBufferCache(), harness.getOnDiskDir(),
                         harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeBulkLoadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeBulkLoadTest.java
index 3fcb4e5..09daaab 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeBulkLoadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeBulkLoadTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, valueProviderFactories,
                 numKeys, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeDeleteTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeDeleteTest.java
index 467916e..f5b4ae4 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeDeleteTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeDeleteTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, valueProviderFactories,
                 numKeys, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeExamplesTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeExamplesTest.java
index a35170c..c94bb48 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeExamplesTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeExamplesTest.java
@@ -37,7 +37,7 @@
     protected ITreeIndex createTreeIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] rtreeCmpFactories,
             IBinaryComparatorFactory[] btreeCmpFactories, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType) throws TreeIndexException {
-        return LSMRTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits, rtreeCmpFactories,
                 btreeCmpFactories, valueProviderFactories, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(),
                 harness.getMergePolicy(), harness.getOperationTracker(), harness.getIOScheduler(),
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeInsertTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeInsertTest.java
index 44da0c0..858f90a 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeInsertTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeInsertTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, valueProviderFactories,
                 numKeys, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeLifecycleTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeLifecycleTest.java
index b97bebb..61692b8 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeLifecycleTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeLifecycleTest.java
@@ -63,7 +63,7 @@
     @Override
     public void setup() throws Exception {
         harness.setUp();
-        testCtx = LSMRTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        testCtx = LSMRTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, valueProviderFactories,
                 numKeys, RTreePolicyType.RTREE, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTest.java
index b13ce4d..436f9b1 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTest.java
@@ -53,7 +53,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeTestContext.create(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeTestContext.create(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), fieldSerdes, valueProviderFactories,
                 numKeys, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(), harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesBulkLoadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesBulkLoadTest.java
index 2baf485..97a3dcc 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesBulkLoadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesBulkLoadTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCache(),
+        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 fieldSerdes, valueProviderFactories, numKeys, rtreePolicyType, harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesDeleteTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesDeleteTest.java
index 9c440cc..843dcc7 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesDeleteTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesDeleteTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCache(),
+        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 fieldSerdes, valueProviderFactories, numKeys, rtreePolicyType, harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesExamplesTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesExamplesTest.java
index 909d0cd..6ffa59a 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesExamplesTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesExamplesTest.java
@@ -37,7 +37,7 @@
     protected ITreeIndex createTreeIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] rtreeCmpFactories,
             IBinaryComparatorFactory[] btreeCmpFactories, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType) throws TreeIndexException {
-        return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(harness.getVirtualBufferCache(),
+        return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits,
                 rtreeCmpFactories, btreeCmpFactories, valueProviderFactories, rtreePolicyType,
                 harness.getMergePolicy(), harness.getOperationTracker(), harness.getIOScheduler(),
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesInsertTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesInsertTest.java
index 6b35192..1e1f46d 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesInsertTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesInsertTest.java
@@ -54,7 +54,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCache(),
+        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 fieldSerdes, valueProviderFactories, numKeys, rtreePolicyType, harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesLifecycleTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesLifecycleTest.java
index 6dcbdf2..607e980 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesLifecycleTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesLifecycleTest.java
@@ -63,7 +63,7 @@
     @Override
     public void setup() throws Exception {
         harness.setUp();
-        testCtx = LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCache(),
+        testCtx = LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 fieldSerdes, valueProviderFactories, numKeys, RTreePolicyType.RTREE, harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesMergeTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesMergeTest.java
index dc81fc3..bdd80aa 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesMergeTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/LSMRTreeWithAntiMatterTuplesMergeTest.java
@@ -53,7 +53,7 @@
     protected AbstractRTreeTestContext createTestContext(ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeys, RTreePolicyType rtreePolicyType)
             throws Exception {
-        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCache(),
+        return LSMRTreeWithAntiMatterTuplesTestContext.create(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(),
                 fieldSerdes, valueProviderFactories, numKeys, rtreePolicyType, harness.getMergePolicy(),
                 harness.getOperationTracker(), harness.getIOScheduler(), harness.getIOOperationCallbackProvider());
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeMultiThreadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeMultiThreadTest.java
index 850d540..0c0d804 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeMultiThreadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeMultiThreadTest.java
@@ -57,7 +57,7 @@
     protected ITreeIndex createTreeIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] rtreeCmpFactories,
             IBinaryComparatorFactory[] btreeCmpFactories, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType) throws TreeIndexException {
-        return LSMRTreeUtils.createLSMTree(harness.getVirtualBufferCache(), harness.getFileReference(),
+        return LSMRTreeUtils.createLSMTree(harness.getVirtualBufferCaches(), harness.getFileReference(),
                 harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits, rtreeCmpFactories,
                 btreeCmpFactories, valueProviderFactories, rtreePolicyType, harness.getBoomFilterFalsePositiveRate(),
                 harness.getMergePolicy(), harness.getOperationTracker(), harness.getIOScheduler(),
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesMultiThreadTest.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesMultiThreadTest.java
index 4a6b462..8b54373 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesMultiThreadTest.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesMultiThreadTest.java
@@ -57,7 +57,7 @@
     protected ITreeIndex createTreeIndex(ITypeTraits[] typeTraits, IBinaryComparatorFactory[] rtreeCmpFactories,
             IBinaryComparatorFactory[] btreeCmpFactories, IPrimitiveValueProviderFactory[] valueProviderFactories,
             RTreePolicyType rtreePolicyType) throws TreeIndexException {
-        return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(harness.getVirtualBufferCache(),
+        return LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(harness.getVirtualBufferCaches(),
                 harness.getFileReference(), harness.getDiskBufferCache(), harness.getDiskFileMapProvider(), typeTraits,
                 rtreeCmpFactories, btreeCmpFactories, valueProviderFactories, rtreePolicyType,
                 harness.getMergePolicy(), harness.getOperationTracker(), harness.getIOScheduler(),
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestContext.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestContext.java
index 8c59e31..9536e96 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestContext.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestContext.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.util;
 
 import java.util.Collection;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
@@ -66,7 +67,7 @@
         return lsmTree.getComparatorFactories();
     }
 
-    public static LSMRTreeTestContext create(IVirtualBufferCache virtualBufferCache, FileReference file,
+    public static LSMRTreeTestContext create(List<IVirtualBufferCache> virtualBufferCaches, FileReference file,
             IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider, ISerializerDeserializer[] fieldSerdes,
             IPrimitiveValueProviderFactory[] valueProviderFactories, int numKeyFields, RTreePolicyType rtreePolicyType,
             double bloomFilterFalsePositiveRate, ILSMMergePolicy mergePolicy, ILSMOperationTracker opTracker,
@@ -77,7 +78,7 @@
                 .serdesToComparatorFactories(fieldSerdes, numKeyFields);
         IBinaryComparatorFactory[] btreeCmpFactories = SerdeUtils.serdesToComparatorFactories(fieldSerdes,
                 fieldSerdes.length);
-        LSMRTree lsmTree = LSMRTreeUtils.createLSMTree(virtualBufferCache, file, diskBufferCache, diskFileMapProvider,
+        LSMRTree lsmTree = LSMRTreeUtils.createLSMTree(virtualBufferCaches, file, diskBufferCache, diskFileMapProvider,
                 typeTraits, rtreeCmpFactories, btreeCmpFactories, valueProviderFactories, rtreePolicyType,
                 bloomFilterFalsePositiveRate, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider,
                 LSMRTreeUtils.proposeBestLinearizer(typeTraits, rtreeCmpFactories.length));
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestHarness.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestHarness.java
index 118b1bc..b67274e 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestHarness.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeTestHarness.java
@@ -18,7 +18,9 @@
 import java.io.File;
 import java.io.FilenameFilter;
 import java.text.SimpleDateFormat;
+import java.util.ArrayList;
 import java.util.Date;
+import java.util.List;
 import java.util.Random;
 import java.util.logging.Logger;
 
@@ -57,12 +59,13 @@
     protected final int memNumPages;
     protected final int hyracksFrameSize;
     protected final double bloomFilterFalsePositiveRate;
+    protected final int numMutableComponents;
 
     protected IOManager ioManager;
     protected int ioDeviceId;
     protected IBufferCache diskBufferCache;
     protected IFileMapProvider diskFileMapProvider;
-    protected IVirtualBufferCache virtualBufferCache;
+    protected List<IVirtualBufferCache> virtualBufferCaches;
     protected IHyracksTaskContext ctx;
     protected ILSMIOOperationScheduler ioScheduler;
     protected ILSMIOOperationCallbackProvider ioOpCallbackProvider;
@@ -87,20 +90,7 @@
         this.mergePolicy = NoMergePolicy.INSTANCE;
         this.opTracker = new ThreadCountingTracker();
         this.ioOpCallbackProvider = NoOpIOOperationCallback.INSTANCE;
-    }
-
-    public LSMRTreeTestHarness(int diskPageSize, int diskNumPages, int diskMaxOpenFiles, int memPageSize,
-            int memNumPages, int hyracksFrameSize, double bloomFilterFalsePositiveRate) {
-        this.diskPageSize = diskPageSize;
-        this.diskNumPages = diskNumPages;
-        this.diskMaxOpenFiles = diskMaxOpenFiles;
-        this.memPageSize = memPageSize;
-        this.memNumPages = memNumPages;
-        this.bloomFilterFalsePositiveRate = bloomFilterFalsePositiveRate;
-        this.hyracksFrameSize = hyracksFrameSize;
-        this.ioScheduler = SynchronousScheduler.INSTANCE;
-        this.mergePolicy = NoMergePolicy.INSTANCE;
-        this.opTracker = new ThreadCountingTracker();
+        this.numMutableComponents = AccessMethodTestsConfig.LSM_RTREE_NUM_MUTABLE_COMPONENTS;
     }
 
     public void setUp() throws HyracksException {
@@ -113,7 +103,12 @@
         TestStorageManagerComponentHolder.init(diskPageSize, diskNumPages, diskMaxOpenFiles);
         diskBufferCache = TestStorageManagerComponentHolder.getBufferCache(ctx);
         diskFileMapProvider = TestStorageManagerComponentHolder.getFileMapProvider(ctx);
-        virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), memPageSize, memNumPages);
+        virtualBufferCaches = new ArrayList<IVirtualBufferCache>();
+        for (int i = 0; i < numMutableComponents; i++) {
+            IVirtualBufferCache virtualBufferCache = new VirtualBufferCache(new HeapBufferAllocator(), memPageSize,
+                    memNumPages / numMutableComponents);
+            virtualBufferCaches.add(virtualBufferCache);
+        }
         rnd.setSeed(RANDOM_SEED);
     }
 
@@ -175,8 +170,8 @@
         return diskFileMapProvider;
     }
 
-    public IVirtualBufferCache getVirtualBufferCache() {
-        return virtualBufferCache;
+    public List<IVirtualBufferCache> getVirtualBufferCaches() {
+        return virtualBufferCaches;
     }
 
     public double getBoomFilterFalsePositiveRate() {
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeWithAntiMatterTuplesTestContext.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeWithAntiMatterTuplesTestContext.java
index 95716f6..069524c 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeWithAntiMatterTuplesTestContext.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/util/LSMRTreeWithAntiMatterTuplesTestContext.java
@@ -16,6 +16,7 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.util;
 
 import java.util.Collection;
+import java.util.List;
 
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
 import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
@@ -67,7 +68,7 @@
         return lsmTree.getComparatorFactories();
     }
 
-    public static LSMRTreeWithAntiMatterTuplesTestContext create(IVirtualBufferCache virtualBufferCache,
+    public static LSMRTreeWithAntiMatterTuplesTestContext create(List<IVirtualBufferCache> virtualBufferCaches,
             FileReference file, IBufferCache diskBufferCache, IFileMapProvider diskFileMapProvider,
             ISerializerDeserializer[] fieldSerdes, IPrimitiveValueProviderFactory[] valueProviderFactories,
             int numKeyFields, RTreePolicyType rtreePolicyType, ILSMMergePolicy mergePolicy,
@@ -78,7 +79,7 @@
                 .serdesToComparatorFactories(fieldSerdes, numKeyFields);
         IBinaryComparatorFactory[] btreeCmpFactories = SerdeUtils.serdesToComparatorFactories(fieldSerdes,
                 fieldSerdes.length);
-        LSMRTreeWithAntiMatterTuples lsmTree = LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(virtualBufferCache,
+        LSMRTreeWithAntiMatterTuples lsmTree = LSMRTreeUtils.createLSMTreeWithAntiMatterTuples(virtualBufferCaches,
                 file, diskBufferCache, diskFileMapProvider, typeTraits, rtreeCmpFactories, btreeCmpFactories,
                 valueProviderFactories, rtreePolicyType, mergePolicy, opTracker, ioScheduler, ioOpCallbackProvider,
                 LSMRTreeUtils.proposeBestLinearizer(typeTraits, rtreeCmpFactories.length));
diff --git a/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
index 496d066..adcb702 100644
--- a/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
+++ b/pregelix/pregelix-dataflow/src/main/java/edu/uci/ics/pregelix/dataflow/context/RuntimeContext.java
@@ -54,14 +54,14 @@
     private final ILocalResourceRepository localResourceRepository;
     private final ResourceIdFactory resourceIdFactory;
     private final IBufferCache bufferCache;
-    private final IVirtualBufferCache vBufferCache;
+    private final List<IVirtualBufferCache> vbcs;
     private final IFileMapManager fileMapManager;
     private final IOManager ioManager;
     private final Map<Long, List<FileReference>> iterationToFiles = new ConcurrentHashMap<Long, List<FileReference>>();
     private final Map<StateKey, IStateObject> appStateMap = new ConcurrentHashMap<StateKey, IStateObject>();
     private final Map<String, Long> jobIdToSuperStep = new ConcurrentHashMap<String, Long>();
     private final Map<String, Boolean> jobIdToMove = new ConcurrentHashMap<String, Boolean>();
-    
+
     private final ThreadFactory threadFactory = new ThreadFactory() {
         public Thread newThread(Runnable r) {
             return new Thread(r);
@@ -81,8 +81,10 @@
                 new PreDelayPageCleanerPolicy(Long.MAX_VALUE), fileMapManager, pageSize, numPages, 1000000,
                 threadFactory);
         int numPagesInMemComponents = numPages / 8;
-        vBufferCache = new MultitenantVirtualBufferCache(new VirtualBufferCache(new HeapBufferAllocator(), pageSize,
-                numPagesInMemComponents));
+        vbcs = new ArrayList<IVirtualBufferCache>();
+        IVirtualBufferCache vBufferCache = new MultitenantVirtualBufferCache(new VirtualBufferCache(
+                new HeapBufferAllocator(), pageSize, numPagesInMemComponents));
+        vbcs.add(vBufferCache);
         ioManager = (IOManager) appCtx.getRootContext().getIOManager();
         lcManager = new NoBudgetIndexLifecycleManager();
         localResourceRepository = new TransientLocalResourceRepository();
@@ -129,8 +131,8 @@
         return bufferCache;
     }
 
-    public IVirtualBufferCache getVirtualBufferCache() {
-        return vBufferCache;
+    public List<IVirtualBufferCache> getVirtualBufferCaches() {
+        return vbcs;
     }
 
     public IFileMapProvider getFileMapManager() {
diff --git a/pregelix/pregelix-runtime/src/main/java/edu/uci/ics/pregelix/runtime/bootstrap/VirtualBufferCacheProvider.java b/pregelix/pregelix-runtime/src/main/java/edu/uci/ics/pregelix/runtime/bootstrap/VirtualBufferCacheProvider.java
index ec51047..f15b1c2 100644
--- a/pregelix/pregelix-runtime/src/main/java/edu/uci/ics/pregelix/runtime/bootstrap/VirtualBufferCacheProvider.java
+++ b/pregelix/pregelix-runtime/src/main/java/edu/uci/ics/pregelix/runtime/bootstrap/VirtualBufferCacheProvider.java
@@ -14,6 +14,8 @@
  */
 package edu.uci.ics.pregelix.runtime.bootstrap;
 
+import java.util.List;
+
 import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCacheProvider;
@@ -33,7 +35,7 @@
     }
     
     @Override
-    public synchronized IVirtualBufferCache getVirtualBufferCache(IHyracksTaskContext ctx) {
-        return RuntimeContext.get(ctx).getVirtualBufferCache();
+    public synchronized List<IVirtualBufferCache> getVirtualBufferCaches(IHyracksTaskContext ctx) {
+        return RuntimeContext.get(ctx).getVirtualBufferCaches();
     }
 }