diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index ee868319377..e512d417729 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -330,6 +330,9 @@ Release 2.0.3-alpha - Unreleased
     HDFS-4307. SocketCache should use monotonic time. (Colin Patrick McCabe
     via atm)
 
+    HDFS-4315. DNs with multiple BPs can have BPOfferServices fail to start
+    due to unsynchronized map access. (atm)
+
   BREAKDOWN OF HDFS-3077 SUBTASKS
 
     HDFS-3077. Quorum-based protocol for reading and writing edit logs.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
index 870d71f1592..cd6b7ccd910 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
@@ -26,6 +26,7 @@
 import java.nio.channels.FileLock;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
@@ -78,7 +79,7 @@ public class DataStorage extends Storage {
   
   // BlockPoolStorage is map of <Block pool Id, BlockPoolStorage>
   private Map<String, BlockPoolSliceStorage> bpStorageMap
-    = new HashMap<String, BlockPoolSliceStorage>();
+      = Collections.synchronizedMap(new HashMap<String, BlockPoolSliceStorage>());
 
 
   DataStorage() {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithMultipleNameNodes.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithMultipleNameNodes.java
index 5d3272af7ac..335c346cee1 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithMultipleNameNodes.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsWithMultipleNameNodes.java
@@ -56,7 +56,6 @@ static private void setLogLevel() {
     ((Log4JLogger)NameNode.stateChangeLog).getLogger().setLevel(Level.OFF);
     ((Log4JLogger)LeaseManager.LOG).getLogger().setLevel(Level.OFF);
     ((Log4JLogger)LogFactory.getLog(FSNamesystem.class)).getLogger().setLevel(Level.OFF);
-    ((Log4JLogger)DataNode.LOG).getLogger().setLevel(Level.OFF);
   }
 
   private static final Configuration conf = new HdfsConfiguration();