diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index d34f4664c15..2ab56720364 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -2,6 +2,11 @@ Hadoop HDFS Change Log
 
 Release 0.23-PB - Unreleased
 
+  NEW FEATURES
+
+    HDFS-395.  DFS Scalability: Incremental block reports. (Tomasz Nykiel
+               via hairong)
+
   IMPROVEMENTS
 
     HDFS-2018. Move all journal stream management code into one place.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
index 84a866f3d05..250781320c7 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
@@ -59,10 +59,12 @@ import org.apache.hadoop.hdfs.server.namenode.INodeFile;
 import org.apache.hadoop.hdfs.server.namenode.INodeFileUnderConstruction;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.Namesystem;
+import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
 import org.apache.hadoop.hdfs.server.protocol.BlocksWithLocations;
 import org.apache.hadoop.hdfs.server.protocol.BlocksWithLocations.BlockWithLocations;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
 import org.apache.hadoop.hdfs.server.protocol.KeyUpdateCommand;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.net.Node;
 import org.apache.hadoop.util.Daemon;
 
@@ -2006,7 +2008,7 @@ public class BlockManager {
    * Modify (block-->datanode) map. Possibly generate replication tasks, if the
    * removed block is still valid.
    */
-  private void removeStoredBlock(Block block, DatanodeDescriptor node) {
+  public void removeStoredBlock(Block block, DatanodeDescriptor node) {
     if(NameNode.stateChangeLog.isDebugEnabled()) {
       NameNode.stateChangeLog.debug("BLOCK* removeStoredBlock: "
           + block + " from " + node.getName());
@@ -2125,27 +2127,48 @@ public class BlockManager {
     }
   }
 
-  /** The given node is reporting that it received a certain block. */
-  public void blockReceived(final DatanodeID nodeID, final String poolId,
-      final Block block, final String delHint) throws IOException {
+  /** The given node is reporting that it received/deleted certain blocks. */
+  public void blockReceivedAndDeleted(final DatanodeID nodeID, 
+     final String poolId, 
+     final ReceivedDeletedBlockInfo receivedAndDeletedBlocks[]
+  ) throws IOException {
     namesystem.writeLock();
+    int received = 0;
+    int deleted = 0;
     try {
       final DatanodeDescriptor node = datanodeManager.getDatanode(nodeID);
       if (node == null || !node.isAlive) {
-        final String s = block + " is received from dead or unregistered node "
-            + nodeID.getName();
-        NameNode.stateChangeLog.warn("BLOCK* blockReceived: " + s);
-        throw new IOException(s);
-      } 
-
-      if (NameNode.stateChangeLog.isDebugEnabled()) {
-        NameNode.stateChangeLog.debug("BLOCK* blockReceived: " + block
-            + " is received from " + nodeID.getName());
+        NameNode.stateChangeLog
+            .warn("BLOCK* blockReceivedDeleted"
+                + " is received from dead or unregistered node "
+                + nodeID.getName());
+        throw new IOException(
+            "Got blockReceivedDeleted message from unregistered or dead node");
       }
 
-      addBlock(node, block, delHint);
+      for (int i = 0; i < receivedAndDeletedBlocks.length; i++) {
+        if (receivedAndDeletedBlocks[i].isDeletedBlock()) {
+          removeStoredBlock(
+              receivedAndDeletedBlocks[i].getBlock(), node);
+          deleted++;
+        } else {
+          addBlock(node, receivedAndDeletedBlocks[i].getBlock(),
+              receivedAndDeletedBlocks[i].getDelHints());
+          received++;
+        }
+        if (NameNode.stateChangeLog.isDebugEnabled()) {
+          NameNode.stateChangeLog.debug("BLOCK* block"
+              + (receivedAndDeletedBlocks[i].isDeletedBlock() ? "Deleted"
+                  : "Received") + ": " + receivedAndDeletedBlocks[i].getBlock()
+              + " is received from " + nodeID.getName());
+        }
+      }
     } finally {
       namesystem.writeUnlock();
+      NameNode.stateChangeLog
+          .debug("*BLOCK* NameNode.blockReceivedAndDeleted: " + "from "
+              + nodeID.getName() + " received: " + received + ", "
+              + " deleted: " + deleted);
     }
   }
 
@@ -2320,6 +2343,7 @@ public class BlockManager {
   }
 
   public void removeBlock(Block block) {
+    block.setNumBytes(BlockCommand.NO_ACK);
     addToInvalidates(block);
     corruptReplicas.removeFromCorruptReplicasMap(block);
     blocksMap.removeBlock(block);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java
index a58de18f04c..ba5226f2e24 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java
@@ -49,6 +49,7 @@ import org.apache.hadoop.hdfs.server.protocol.DisallowedDatanodeException;
 import org.apache.hadoop.hdfs.server.protocol.FinalizeCommand;
 import org.apache.hadoop.hdfs.server.protocol.KeyUpdateCommand;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.server.protocol.UpgradeCommand;
 import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.ipc.RemoteException;
@@ -87,6 +88,7 @@ class BPOfferService implements Runnable {
   DatanodeRegistration bpRegistration;
   
   long lastBlockReport = 0;
+  long lastDeletedReport = 0;
 
   boolean resetBlockReportTime = true;
 
@@ -94,8 +96,9 @@ class BPOfferService implements Runnable {
   DatanodeProtocol bpNamenode;
   private long lastHeartbeat = 0;
   private volatile boolean initialized = false;
-  private final LinkedList<Block> receivedBlockList = new LinkedList<Block>();
-  private final LinkedList<String> delHints = new LinkedList<String>();
+  private final LinkedList<ReceivedDeletedBlockInfo> receivedAndDeletedBlockList 
+  	= new LinkedList<ReceivedDeletedBlockInfo>();
+  private volatile int pendingReceivedRequests = 0;
   private volatile boolean shouldServiceRun = true;
   UpgradeManagerDatanode upgradeManager = null;
   private final DataNode dn;
@@ -271,39 +274,30 @@ class BPOfferService implements Runnable {
    * Report received blocks and delete hints to the Namenode
    * @throws IOException
    */
-  private void reportReceivedBlocks() throws IOException {
-    //check if there are newly received blocks
-    Block [] blockArray=null;
-    String [] delHintArray=null;
-    synchronized(receivedBlockList) {
-      synchronized(delHints){
-        int numBlocks = receivedBlockList.size();
-        if (numBlocks > 0) {
-          if(numBlocks!=delHints.size()) {
-            LOG.warn("Panic: receiveBlockList and delHints are not of " +
-            "the same length" );
-          }
-          //
-          // Send newly-received blockids to namenode
-          //
-          blockArray = receivedBlockList.toArray(new Block[numBlocks]);
-          delHintArray = delHints.toArray(new String[numBlocks]);
-        }
+  private void reportReceivedDeletedBlocks() throws IOException {
+
+    // check if there are newly received blocks
+    ReceivedDeletedBlockInfo[] receivedAndDeletedBlockArray = null;
+    int currentReceivedRequestsCounter;
+    synchronized (receivedAndDeletedBlockList) {
+      currentReceivedRequestsCounter = pendingReceivedRequests;
+      int numBlocks = receivedAndDeletedBlockList.size();
+      if (numBlocks > 0) {
+        //
+        // Send newly-received and deleted blockids to namenode
+        //
+        receivedAndDeletedBlockArray = receivedAndDeletedBlockList
+            .toArray(new ReceivedDeletedBlockInfo[numBlocks]);
       }
     }
-    if (blockArray != null) {
-      if(delHintArray == null || delHintArray.length != blockArray.length ) {
-        LOG.warn("Panic: block array & delHintArray are not the same" );
-      }
-      bpNamenode.blockReceived(bpRegistration, getBlockPoolId(), blockArray,
-          delHintArray);
-      synchronized(receivedBlockList) {
-        synchronized(delHints){
-          for(int i=0; i<blockArray.length; i++) {
-            receivedBlockList.remove(blockArray[i]);
-            delHints.remove(delHintArray[i]);
-          }
+    if (receivedAndDeletedBlockArray != null) {
+      bpNamenode.blockReceivedAndDeleted(bpRegistration, getBlockPoolId(),
+          receivedAndDeletedBlockArray);
+      synchronized (receivedAndDeletedBlockList) {
+        for (int i = 0; i < receivedAndDeletedBlockArray.length; i++) {
+          receivedAndDeletedBlockList.remove(receivedAndDeletedBlockArray[i]);
         }
+        pendingReceivedRequests -= currentReceivedRequestsCounter;
       }
     }
   }
@@ -314,26 +308,42 @@ class BPOfferService implements Runnable {
    * client? For now we don't.
    */
   void notifyNamenodeReceivedBlock(ExtendedBlock block, String delHint) {
-    if(block==null || delHint==null) {
-      throw new IllegalArgumentException(
-          block==null?"Block is null":"delHint is null");
+    if (block == null || delHint == null) {
+      throw new IllegalArgumentException(block == null ? "Block is null"
+          : "delHint is null");
     }
-    
+
     if (!block.getBlockPoolId().equals(getBlockPoolId())) {
       LOG.warn("BlockPool mismatch " + block.getBlockPoolId() + " vs. "
           + getBlockPoolId());
       return;
     }
-    
-    synchronized (receivedBlockList) {
-      synchronized (delHints) {
-        receivedBlockList.add(block.getLocalBlock());
-        delHints.add(delHint);
-        receivedBlockList.notifyAll();
-      }
+
+    synchronized (receivedAndDeletedBlockList) {
+      receivedAndDeletedBlockList.add(new ReceivedDeletedBlockInfo(block
+          .getLocalBlock(), delHint));
+      pendingReceivedRequests++;
+      receivedAndDeletedBlockList.notifyAll();
     }
   }
 
+  void notifyNamenodeDeletedBlock(ExtendedBlock block) {
+    if (block == null) {
+      throw new IllegalArgumentException("Block is null");
+    }
+
+    if (!block.getBlockPoolId().equals(getBlockPoolId())) {
+      LOG.warn("BlockPool mismatch " + block.getBlockPoolId() + " vs. "
+          + getBlockPoolId());
+      return;
+    }
+
+    synchronized (receivedAndDeletedBlockList) {
+      receivedAndDeletedBlockList.add(new ReceivedDeletedBlockInfo(block
+          .getLocalBlock(), ReceivedDeletedBlockInfo.TODELETE_HINT));
+    }
+  }
+  
 
   /**
    * Report the list blocks to the Namenode
@@ -443,7 +453,8 @@ class BPOfferService implements Runnable {
    * forever calling remote NameNode functions.
    */
   private void offerService() throws Exception {
-    LOG.info("For namenode " + nnAddr + " using BLOCKREPORT_INTERVAL of "
+    LOG.info("For namenode " + nnAddr + " using DELETEREPORT_INTERVAL of "
+        + dnConf.deleteReportInterval + " msec " + " BLOCKREPORT_INTERVAL of "
         + dnConf.blockReportInterval + "msec" + " Initial delay: "
         + dnConf.initialBlockReportDelay + "msec" + "; heartBeatInterval="
         + dnConf.heartBeatInterval);
@@ -481,8 +492,11 @@ class BPOfferService implements Runnable {
             }
           }
         }
-
-        reportReceivedBlocks();
+        if (pendingReceivedRequests > 0
+            || (startTime - lastDeletedReport > dnConf.deleteReportInterval)) {
+          reportReceivedDeletedBlocks();
+          lastDeletedReport = startTime;
+        }
 
         DatanodeCommand cmd = blockReport();
         processCommand(cmd);
@@ -498,10 +512,10 @@ class BPOfferService implements Runnable {
         //
         long waitTime = dnConf.heartBeatInterval - 
         (System.currentTimeMillis() - lastHeartbeat);
-        synchronized(receivedBlockList) {
-          if (waitTime > 0 && receivedBlockList.size() == 0) {
+        synchronized(receivedAndDeletedBlockList) {
+          if (waitTime > 0 && pendingReceivedRequests == 0) {
             try {
-              receivedBlockList.wait(waitTime);
+            	receivedAndDeletedBlockList.wait(waitTime);
             } catch (InterruptedException ie) {
               LOG.warn("BPOfferService for " + this + " interrupted");
             }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java
index f0f4737df92..e4bf9a676dc 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java
@@ -55,6 +55,7 @@ class DNConf {
   final long readaheadLength;
   final long heartBeatInterval;
   final long blockReportInterval;
+  final long deleteReportInterval;
   final long initialBlockReportDelay;
   final int writePacketSize;
 
@@ -105,6 +106,7 @@ class DNConf {
     heartBeatInterval = conf.getLong(DFS_HEARTBEAT_INTERVAL_KEY,
         DFS_HEARTBEAT_INTERVAL_DEFAULT) * 1000L;
     
+    this.deleteReportInterval = 100 * heartBeatInterval;
     // do we need to sync block file contents to disk when blockfile is closed?
     this.syncOnClose = conf.getBoolean(DFS_DATANODE_SYNCONCLOSE_KEY, 
         DFS_DATANODE_SYNCONCLOSE_DEFAULT);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
index caeb7a848a4..104eb242847 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
@@ -129,6 +129,7 @@ import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.hdfs.server.protocol.InterDatanodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.server.protocol.ReplicaRecoveryInfo;
 import org.apache.hadoop.hdfs.server.protocolR23Compatible.InterDatanodeProtocolServerSideTranslatorR23;
 import org.apache.hadoop.hdfs.server.protocolR23Compatible.InterDatanodeProtocolTranslatorR23;
@@ -659,6 +660,17 @@ public class DataNode extends Configured
     }
   }
   
+  // calls specific to BP
+  protected void notifyNamenodeDeletedBlock(ExtendedBlock block) {
+    BPOfferService bpos = blockPoolManager.get(block.getBlockPoolId());
+    if (bpos != null) {
+      bpos.notifyNamenodeDeletedBlock(block);
+    } else {
+      LOG.warn("Cannot find BPOfferService for reporting block deleted for bpid="
+          + block.getBlockPoolId());
+    }
+  }
+  
   public void reportBadBlocks(ExtendedBlock block) throws IOException{
     BPOfferService bpos = blockPoolManager.get(block.getBlockPoolId());
     if(bpos == null || bpos.bpNamenode == null) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDataset.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDataset.java
index b2e3cd4aa4d..52708bfa82e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDataset.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDataset.java
@@ -1182,7 +1182,7 @@ public class FSDataset implements FSDatasetInterface {
     for (int idx = 0; idx < storage.getNumStorageDirs(); idx++) {
       roots[idx] = storage.getStorageDir(idx).getCurrentDir();
     }
-    asyncDiskService = new FSDatasetAsyncDiskService(roots);
+    asyncDiskService = new FSDatasetAsyncDiskService(this, roots);
     registerMBean(storage.getStorageID());
   }
 
@@ -2116,15 +2116,19 @@ public class FSDataset implements FSDatasetInterface {
         volumeMap.remove(bpid, invalidBlks[i]);
       }
       File metaFile = getMetaFile(f, invalidBlks[i].getGenerationStamp());
-      
+
       // Delete the block asynchronously to make sure we can do it fast enough
-      asyncDiskService.deleteAsync(v, bpid, f, metaFile,
-          invalidBlks[i].toString());
+      asyncDiskService.deleteAsync(v, f, metaFile,
+          new ExtendedBlock(bpid, invalidBlks[i]));
     }
     if (error) {
       throw new IOException("Error in deleting blocks.");
     }
   }
+  
+  public void notifyNamenodeDeletedBlock(ExtendedBlock block){
+    datanode.notifyNamenodeDeletedBlock(block);
+  }
 
   /**
    * Turn the block identifier into a filename; ignore generation stamp!!!
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDatasetAsyncDiskService.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDatasetAsyncDiskService.java
index 0c2523b8341..408a6afc472 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDatasetAsyncDiskService.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/FSDatasetAsyncDiskService.java
@@ -28,6 +28,8 @@ import java.util.concurrent.TimeUnit;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
 
 /*
  * This class is a container of multiple thread pools, each for a volume,
@@ -47,6 +49,8 @@ import org.apache.commons.logging.LogFactory;
  */
 class FSDatasetAsyncDiskService {
   
+  final FSDataset dataset;
+  
   public static final Log LOG = LogFactory.getLog(FSDatasetAsyncDiskService.class);
   
   // ThreadPool core pool size
@@ -70,8 +74,8 @@ class FSDatasetAsyncDiskService {
    * 
    * @param volumes The roots of the data volumes.
    */
-  FSDatasetAsyncDiskService(File[] volumes) {
-
+  FSDatasetAsyncDiskService(FSDataset dataset, File[] volumes) {
+    this.dataset = dataset;
     // Create one ThreadPool per volume
     for (int v = 0 ; v < volumes.length; v++) {
       final File vol = volumes[v];
@@ -147,13 +151,12 @@ class FSDatasetAsyncDiskService {
    * Delete the block file and meta file from the disk asynchronously, adjust
    * dfsUsed statistics accordingly.
    */
-  void deleteAsync(FSDataset.FSVolume volume, String bpid, File blockFile,
-      File metaFile, String blockName) {
-    DataNode.LOG.info("Scheduling block " + blockName + " file " + blockFile
-        + " for deletion");
-    ReplicaFileDeleteTask deletionTask = 
-        new ReplicaFileDeleteTask(volume, bpid, blockFile, metaFile,
-            blockName);
+  void deleteAsync(FSDataset.FSVolume volume, File blockFile, File metaFile,
+      ExtendedBlock block) {
+    DataNode.LOG.info("Scheduling block " + block.getLocalBlock().toString()
+        + " file " + blockFile + " for deletion");
+    ReplicaFileDeleteTask deletionTask = new ReplicaFileDeleteTask(dataset,
+        volume, blockFile, metaFile, block);
     execute(volume.getCurrentDir(), deletionTask);
   }
   
@@ -161,19 +164,19 @@ class FSDatasetAsyncDiskService {
    *  as decrement the dfs usage of the volume. 
    */
   static class ReplicaFileDeleteTask implements Runnable {
+    final FSDataset dataset;
     final FSDataset.FSVolume volume;
-    final String blockPoolId;
     final File blockFile;
     final File metaFile;
-    final String blockName;
+    final ExtendedBlock block;
     
-    ReplicaFileDeleteTask(FSDataset.FSVolume volume, String bpid,
-        File blockFile, File metaFile, String blockName) {
+    ReplicaFileDeleteTask(FSDataset dataset, FSDataset.FSVolume volume, File blockFile,
+        File metaFile, ExtendedBlock block) {
+      this.dataset = dataset;
       this.volume = volume;
-      this.blockPoolId = bpid;
       this.blockFile = blockFile;
       this.metaFile = metaFile;
-      this.blockName = blockName;
+      this.block = block;
     }
     
     FSDataset.FSVolume getVolume() {
@@ -183,9 +186,9 @@ class FSDatasetAsyncDiskService {
     @Override
     public String toString() {
       // Called in AsyncDiskService.execute for displaying error messages.
-      return "deletion of block " + blockPoolId + " " + blockName
-          + " with block file " + blockFile + " and meta file " + metaFile
-          + " from volume " + volume;
+      return "deletion of block " + block.getBlockPoolId() + " "
+          + block.getLocalBlock().toString() + " with block file " + blockFile
+          + " and meta file " + metaFile + " from volume " + volume;
     }
 
     @Override
@@ -193,12 +196,15 @@ class FSDatasetAsyncDiskService {
       long dfsBytes = blockFile.length() + metaFile.length();
       if ( !blockFile.delete() || ( !metaFile.delete() && metaFile.exists() ) ) {
         DataNode.LOG.warn("Unexpected error trying to delete block "
-            + blockPoolId + " " + blockName + " at file " + blockFile
-            + ". Ignored.");
+            + block.getBlockPoolId() + " " + block.getLocalBlock().toString()
+            + " at file " + blockFile + ". Ignored.");
       } else {
-        volume.decDfsUsed(blockPoolId, dfsBytes);
-        DataNode.LOG.info("Deleted block " + blockPoolId + " " + blockName
-            + " at file " + blockFile);
+        if(block.getLocalBlock().getNumBytes() != BlockCommand.NO_ACK){
+          dataset.notifyNamenodeDeletedBlock(block);
+        }
+        volume.decDfsUsed(block.getBlockPoolId(), dfsBytes);
+        DataNode.LOG.info("Deleted block " + block.getBlockPoolId() + " "
+            + block.getLocalBlock().toString() + " at file " + blockFile);
       }
     }
   };
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java
index ddf8e3fdf9d..89d68bbf2cd 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java
@@ -77,6 +77,7 @@ import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeRegistration;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
 import org.apache.hadoop.hdfs.server.protocol.NodeRegistration;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.server.protocol.RemoteEditLogManifest;
 import org.apache.hadoop.hdfs.server.protocol.UpgradeCommand;
 import org.apache.hadoop.io.EnumSetWritable;
@@ -820,17 +821,16 @@ class NameNodeRpcServer implements NamenodeProtocols {
   }
 
   @Override // DatanodeProtocol
-  public void blockReceived(DatanodeRegistration nodeReg, String poolId,
-      Block blocks[], String delHints[]) throws IOException {
+  public void blockReceivedAndDeleted(DatanodeRegistration nodeReg, String poolId,
+      ReceivedDeletedBlockInfo[] receivedAndDeletedBlocks) throws IOException {
     verifyRequest(nodeReg);
     if(stateChangeLog.isDebugEnabled()) {
-      stateChangeLog.debug("*BLOCK* NameNode.blockReceived: "
-          +"from "+nodeReg.getName()+" "+blocks.length+" blocks.");
-    }
-    for (int i = 0; i < blocks.length; i++) {
-      namesystem.getBlockManager().blockReceived(
-          nodeReg, poolId, blocks[i], delHints[i]);
+      stateChangeLog.debug("*BLOCK* NameNode.blockReceivedAndDeleted: "
+          +"from "+nodeReg.getName()+" "+receivedAndDeletedBlocks.length
+          +" blocks.");
     }
+    namesystem.getBlockManager().blockReceivedAndDeleted(
+        nodeReg, poolId, receivedAndDeletedBlocks);
   }
   
   @Override // DatanodeProtocol
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/BlockCommand.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/BlockCommand.java
index b4e4ab7de14..d236da36aec 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/BlockCommand.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/BlockCommand.java
@@ -44,6 +44,16 @@ import org.apache.hadoop.io.WritableFactory;
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
 public class BlockCommand extends DatanodeCommand {
+  
+  /**
+   * This constant is used to indicate that the block deletion does not need
+   * explicit ACK from the datanode. When a block is put into the list of blocks
+   * to be deleted, it's size is set to this constant. We assume that no block
+   * would actually have this size. Otherwise, we would miss ACKs for blocks
+   * with such size. Positive number is used for compatibility reasons.
+   */
+  public static final long NO_ACK = Long.MAX_VALUE;
+  
   String poolId;
   Block blocks[];
   DatanodeInfo targets[][];
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/DatanodeProtocol.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/DatanodeProtocol.java
index f60bef7e697..9fb509109ee 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/DatanodeProtocol.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/DatanodeProtocol.java
@@ -126,17 +126,19 @@ public interface DatanodeProtocol extends VersionedProtocol {
                                      long[] blocks) throws IOException;
     
   /**
-   * blockReceived() allows the DataNode to tell the NameNode about
-   * recently-received block data, with a hint for pereferred replica
-   * to be deleted when there is any excessive blocks.
+   * blockReceivedAndDeleted() allows the DataNode to tell the NameNode about
+   * recently-received and -deleted block data. 
+   * 
+   * For the case of received blocks, a hint for preferred replica to be 
+   * deleted when there is any excessive blocks is provided.
    * For example, whenever client code
    * writes a new Block here, or another DataNode copies a Block to
    * this DataNode, it will call blockReceived().
    */
-  public void blockReceived(DatanodeRegistration registration,
+  public void blockReceivedAndDeleted(DatanodeRegistration registration,
                             String poolId,
-                            Block blocks[],
-                            String[] delHints) throws IOException;
+                            ReceivedDeletedBlockInfo[] receivedAndDeletedBlocks)
+                            throws IOException;
 
   /**
    * errorReport() tells the NameNode about something that has gone
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/ReceivedDeletedBlockInfo.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/ReceivedDeletedBlockInfo.java
new file mode 100644
index 00000000000..45014add97b
--- /dev/null
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/ReceivedDeletedBlockInfo.java
@@ -0,0 +1,101 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hdfs.server.protocol;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.hdfs.protocol.Block;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.Writable;
+
+/**
+ * A data structure to store Block and delHints together, used to send
+ * received/deleted ACKs.
+ */
+public class ReceivedDeletedBlockInfo implements Writable {
+  Block block;
+  String delHints;
+
+  public final static String TODELETE_HINT = "-";
+
+  public ReceivedDeletedBlockInfo() {
+  }
+
+  public ReceivedDeletedBlockInfo(Block blk, String delHints) {
+    this.block = blk;
+    this.delHints = delHints;
+  }
+
+  public Block getBlock() {
+    return this.block;
+  }
+
+  public void setBlock(Block blk) {
+    this.block = blk;
+  }
+
+  public String getDelHints() {
+    return this.delHints;
+  }
+
+  public void setDelHints(String hints) {
+    this.delHints = hints;
+  }
+
+  public boolean equals(Object o) {
+    if (!(o instanceof ReceivedDeletedBlockInfo)) {
+      return false;
+    }
+    ReceivedDeletedBlockInfo other = (ReceivedDeletedBlockInfo) o;
+    return this.block.equals(other.getBlock())
+        && this.delHints.equals(other.delHints);
+  }
+
+  public int hashCode() {
+    assert false : "hashCode not designed";
+    return 0; 
+  }
+
+  public boolean blockEquals(Block b) {
+    return this.block.equals(b);
+  }
+
+  public boolean isDeletedBlock() {
+    return delHints.equals(TODELETE_HINT);
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    this.block.write(out);
+    Text.writeString(out, this.delHints);
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    this.block = new Block();
+    this.block.readFields(in);
+    this.delHints = Text.readString(in);
+  }
+
+  public String toString() {
+    return block.toString() + ", delHint: " + delHints;
+  }
+}
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java
index bac38d2d952..afc003f9381 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/NNThroughputBenchmark.java
@@ -48,6 +48,7 @@ import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.io.EnumSetWritable;
@@ -880,10 +881,10 @@ public class NNThroughputBenchmark {
           receivedDNReg.setStorageInfo(
                           new DataStorage(nsInfo, dnInfo.getStorageID()));
           receivedDNReg.setInfoPort(dnInfo.getInfoPort());
-          nameNodeProto.blockReceived( receivedDNReg, 
-                                  nameNode.getNamesystem().getBlockPoolId(),
-                                  new Block[] {blocks[i]},
-                                  new String[] {DataNode.EMPTY_DEL_HINT});
+          nameNodeProto.blockReceivedAndDeleted(receivedDNReg, nameNode
+              .getNamesystem().getBlockPoolId(),
+              new ReceivedDeletedBlockInfo[] { new ReceivedDeletedBlockInfo(
+                  blocks[i], DataNode.EMPTY_DEL_HINT) });
         }
       }
       return blocks.length;
@@ -995,11 +996,10 @@ public class NNThroughputBenchmark {
         for(DatanodeInfo dnInfo : loc.getLocations()) {
           int dnIdx = Arrays.binarySearch(datanodes, dnInfo.getName());
           datanodes[dnIdx].addBlock(loc.getBlock().getLocalBlock());
-          nameNodeProto.blockReceived(
-              datanodes[dnIdx].dnRegistration, 
-              loc.getBlock().getBlockPoolId(),
-              new Block[] {loc.getBlock().getLocalBlock()},
-              new String[] {""});
+          nameNodeProto.blockReceivedAndDeleted(datanodes[dnIdx].dnRegistration, loc
+              .getBlock().getBlockPoolId(),
+              new ReceivedDeletedBlockInfo[] { new ReceivedDeletedBlockInfo(loc
+                  .getBlock().getLocalBlock(), "") });
         }
       }
       return prevBlock;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
index bfc02360d48..097372c8ce6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeadDatanode.java
@@ -37,6 +37,7 @@ import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.hdfs.server.protocol.RegisterCommand;
+import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.junit.After;
 import org.junit.Test;
 
@@ -105,12 +106,12 @@ public class TestDeadDatanode {
 
     DatanodeProtocol dnp = cluster.getNameNodeRpc();
     
-    Block[] blocks = new Block[] { new Block(0) };
-    String[] delHints = new String[] { "" };
+    ReceivedDeletedBlockInfo[] blocks = { new ReceivedDeletedBlockInfo(
+        new Block(0), "") };
     
     // Ensure blockReceived call from dead datanode is rejected with IOException
     try {
-      dnp.blockReceived(reg, poolId, blocks, delHints);
+      dnp.blockReceivedAndDeleted(reg, poolId, blocks);
       Assert.fail("Expected IOException is not thrown");
     } catch (IOException ex) {
       // Expected