diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 89aede2e1e3..af6f8ae7b56 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -120,6 +120,9 @@ Release 2.7.2 - UNRELEASED
     HDFS-9413. getContentSummary() on standby should throw StandbyException.
     (Brahma Reddy Battula via mingma)
 
+    HDFS-9426. Rollingupgrade finalization is not backward compatible
+    (Kihwal Lee via vinayakumarb)
+
 Release 2.7.1 - 2015-07-06
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolClientSideTranslatorPB.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolClientSideTranslatorPB.java
index 825e83586b3..86422e6cb5d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolClientSideTranslatorPB.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolClientSideTranslatorPB.java
@@ -161,7 +161,11 @@ public class DatanodeProtocolClientSideTranslatorPB implements
       index++;
     }
     RollingUpgradeStatus rollingUpdateStatus = null;
-    if (resp.hasRollingUpgradeStatus()) {
+
+    // Use v2 semantics if available.
+    if (resp.hasRollingUpgradeStatusV2()) {
+      rollingUpdateStatus = PBHelper.convert(resp.getRollingUpgradeStatusV2());
+    } else if (resp.hasRollingUpgradeStatus()) {
       rollingUpdateStatus = PBHelper.convert(resp.getRollingUpgradeStatus());
     }
     return new HeartbeatResponse(cmds, PBHelper.convert(resp.getHaStatus()),
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolServerSideTranslatorPB.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolServerSideTranslatorPB.java
index 873eb6d1708..ca9e4df1aee 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolServerSideTranslatorPB.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolServerSideTranslatorPB.java
@@ -46,6 +46,7 @@ import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.StorageBlock
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.StorageReceivedDeletedBlocksProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeIDProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.LocatedBlockProto;
+import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.RollingUpgradeStatusProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.VersionRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.VersionResponseProto;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
@@ -132,8 +133,15 @@ public class DatanodeProtocolServerSideTranslatorPB implements
     RollingUpgradeStatus rollingUpdateStatus = response
         .getRollingUpdateStatus();
     if (rollingUpdateStatus != null) {
-      builder.setRollingUpgradeStatus(PBHelper
-          .convertRollingUpgradeStatus(rollingUpdateStatus));
+      // V2 is always set for newer datanodes.
+      // To be compatible with older datanodes, V1 is set to null
+      //  if the RU was finalized.
+      RollingUpgradeStatusProto rus = PBHelper.convertRollingUpgradeStatus(
+          rollingUpdateStatus);
+      builder.setRollingUpgradeStatusV2(rus);
+      if (!rollingUpdateStatus.isFinalized()) {
+        builder.setRollingUpgradeStatus(rus);
+      }
     }
     return builder.build();
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto b/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto
index bce5f5677e4..a17d784b313 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto
@@ -217,6 +217,7 @@ message HeartbeatResponseProto {
   repeated DatanodeCommandProto cmds = 1; // Returned commands can be null
   required NNHAStatusHeartbeatProto haStatus = 2;
   optional RollingUpgradeStatusProto rollingUpgradeStatus = 3;
+  optional RollingUpgradeStatusProto rollingUpgradeStatusV2 = 4;
 }
 
 /**