HDFS-930. Better error message for DATA_TRANSFER_VERSION mismatched. Contributed by Kay Kay

git-svn-id: https://svn.apache.org/repos/asf/hadoop/hdfs/trunk@908628 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -63,6 +63,9 @@ Trunk (unreleased changes)
     HDFS-949. Move DelegationToken into Common so that it can be used by
     MapReduce. (omalley)
 
+    HDFS-930. Better error message for DATA_TRANSFER_VERSION mismatched.
+    (Kay Kay via szetszwo)
+
   OPTIMIZATIONS
 
   BUG FIXES

src/java/org/apache/hadoop/hdfs/protocol/DataTransferProtocol.java

@@ -307,7 +307,9 @@ public interface DataTransferProtocol {
     protected final Op readOp(DataInputStream in) throws IOException {
       final short version = in.readShort();
       if (version != DATA_TRANSFER_VERSION) {
-        throw new IOException( "Version Mismatch" );
+        throw new IOException( "Version Mismatch (Expected: " +
+            DataTransferProtocol.DATA_TRANSFER_VERSION  +
+            ", Received: " +  version + " )");
       }
       return Op.read(in);
     }