title: Datanode not starts correctly
body: <p>I am trying to install Hadoop 2.2.0 in pseudo-distributed mode. While I am trying to start the datanode services it is showing the following error, can anyone please tell how to resolve this?</p>
  
  <pre><code>**2**014-03-11 08:48:15,916 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Block pool &lt;registering&gt; (storage id unknown) service to localhost/127.0.0.1:9000 starting to offer service
  2014-03-11 08:48:15,922 INFO org.apache.hadoop.ipc.Server: IPC Server Responder: starting
  2014-03-11 08:48:15,922 INFO org.apache.hadoop.ipc.Server: IPC Server listener on 50020: starting
  2014-03-11 08:48:16,406 INFO org.apache.hadoop.hdfs.server.common.Storage: Lock on /home/prassanna/usr/local/hadoop/yarn_data/hdfs/datanode/in_use.lock acquired by nodename 3627@prassanna-Studio-1558
  2014-03-11 08:48:16,426 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for block pool Block pool BP-611836968-127.0.1.1-1394507838610 (storage id DS-1960076343-127.0.1.1-50010-1394127604582) service to localhost/127.0.0.1:9000
  java.io.IOException: Incompatible clusterIDs in /home/prassanna/usr/local/hadoop/yarn_data/hdfs/datanode: namenode clusterID = CID-fb61aa70-4b15-470e-a1d0-12653e357a10; datanode clusterID = CID-8bf63244-0510-4db6-a949-8f74b50f2be9
      at**** org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:391)
      at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:191)
      at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:219)
      at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:837)
      at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:808)
      at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:280)
      at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:222)
      at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:664)
      at java.lang.Thread.run(Thread.java:662)
  2014-03-11 08:48:16,427 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool BP-611836968-127.0.1.1-1394507838610 (storage id DS-1960076343-127.0.1.1-50010-1394127604582) service to localhost/127.0.0.1:9000
  2014-03-11 08:48:16,532 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Removed Block pool BP-611836968-127.0.1.1-1394507838610 (storage id DS-1960076343-127.0.1.1-50010-1394127604582)
  2014-03-11 08:48:18,532 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Exiting Datanode
  2014-03-11 08:48:18,534 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 0
  2014-03-11 08:48:18,536 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG: 
  </code></pre>