2014-04-07 18:40:44,479 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: prabhathp:50010:DataXceiver error processing unknown operation  src: /127.0.0.1:38572 dest: /127.0.0.1:50010
java.io.IOException: Version Mismatch (Expected: 28, Received: 26738 )
at org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.readOp(Receiver.java:54)
at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:198)
at java.lang.Thread.run(Thread.java:744)