diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index cf179869e5a..2313f13c0bb 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -1193,6 +1193,9 @@ Release 2.6.4 - UNRELEASED
 
   BUG FIXES
 
+    HDFS-9600. do not check replication if the block is under construction
+    (Phil Yang via vinayakumarb)
+
 Release 2.6.3 - 2015-12-17
 
   INCOMPATIBLE CHANGES
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 db50e44469c..ef784d2d40e 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
@@ -3444,7 +3444,14 @@ public class BlockManager {
    * or if it does not have enough racks.
    */
   boolean isNeededReplication(Block b, int expected, int current) {
-    return current < expected || !isPlacementPolicySatisfied(b);
+    BlockInfoContiguous blockInfo;
+    if (b instanceof BlockInfoContiguous) {
+      blockInfo = (BlockInfoContiguous) b;
+    } else {
+      blockInfo = getStoredBlock(b);
+    }
+    return blockInfo.isComplete()
+        && (current < expected || !isPlacementPolicySatisfied(b));
   }
   
   public long getMissingBlocksCount() {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DecommissionManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DecommissionManager.java
index 7f3d77802ec..c76b192c7e9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DecommissionManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DecommissionManager.java
@@ -253,8 +253,9 @@ public class DecommissionManager {
       NumberReplicas numberReplicas) {
     final int numExpected = bc.getBlockReplication();
     final int numLive = numberReplicas.liveReplicas();
-    if (!blockManager.isNeededReplication(block, numExpected, numLive)) {
-      // Block doesn't need replication. Skip.
+    if (numLive >= numExpected
+        && blockManager.isPlacementPolicySatisfied(block)) {
+      // Block has enough replica, skip
       LOG.trace("Block {} does not need replication.", block);
       return true;
     }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java
index 920a18dcff2..196a38b4ce0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java
@@ -30,21 +30,28 @@ import static org.mockito.Mockito.verify;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.EnumSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map.Entry;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CreateFlag;
+import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.StorageType;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.DFSOutputStream;
 import org.apache.hadoop.hdfs.DFSTestUtil;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.BlockTargetPair;
 import org.apache.hadoop.hdfs.server.datanode.DataNodeTestUtils;
 import org.apache.hadoop.hdfs.server.datanode.FinalizedReplica;
@@ -53,8 +60,11 @@ import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorage;
+import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
 import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
 import org.apache.hadoop.hdfs.server.protocol.StorageReceivedDeletedBlocks;
+import org.apache.hadoop.io.EnumSetWritable;
+import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.net.NetworkTopology;
 import org.junit.Assert;
@@ -371,8 +381,58 @@ public class TestBlockManager {
     bm.processMisReplicatedBlocks();
     assertEquals(0, bm.numOfUnderReplicatedBlocks());
   }
-  
-  
+
+  @Test(timeout = 60000)
+  public void testNeededReplicationWhileAppending() throws IOException {
+    Configuration conf = new HdfsConfiguration();
+    String src = "/test-file";
+    Path file = new Path(src);
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).build();
+    cluster.waitActive();
+    try {
+      BlockManager bm = cluster.getNamesystem().getBlockManager();
+      FileSystem fs = cluster.getFileSystem();
+      NamenodeProtocols namenode = cluster.getNameNodeRpc();
+      DFSOutputStream out = null;
+      try {
+        out = (DFSOutputStream) (fs.create(file).
+            getWrappedStream());
+        out.write(1);
+        out.hflush();
+        out.close();
+        FSDataInputStream in = null;
+        ExtendedBlock oldBlock = null;
+        LocatedBlock oldLoactedBlock = null;
+        try {
+          in = fs.open(file);
+          oldLoactedBlock = DFSTestUtil.getAllBlocks(in).get(0);
+          oldBlock = oldLoactedBlock.getBlock();
+        } finally {
+          IOUtils.closeStream(in);
+        }
+        String clientName =
+            ((DistributedFileSystem) fs).getClient().getClientName();
+        namenode.append(src, clientName, new EnumSetWritable<>(
+            EnumSet.of(CreateFlag.APPEND)));
+        LocatedBlock newLocatedBlock =
+            namenode.updateBlockForPipeline(oldBlock, clientName);
+        ExtendedBlock newBlock =
+            new ExtendedBlock(oldBlock.getBlockPoolId(), oldBlock.getBlockId(),
+                oldBlock.getNumBytes(),
+                newLocatedBlock.getBlock().getGenerationStamp());
+        namenode.updatePipeline(clientName, oldBlock, newBlock,
+            oldLoactedBlock.getLocations(), oldLoactedBlock.getStorageIDs());
+        BlockInfoContiguous bi = bm.getStoredBlock(newBlock.getLocalBlock());
+        assertFalse(bm.isNeededReplication(bi,
+            oldLoactedBlock.getLocations().length, bm.countLiveNodes(bi)));
+      } finally {
+        IOUtils.closeStream(out);
+      }
+    } finally {
+      cluster.shutdown();
+    }
+  }
+
   /**
    * Tell the block manager that replication is completed for the given
    * pipeline.