Initialization failed for block pool Block pool

2013-06-08 17:57:27,519 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for block pool Block pool BP-770817654-172.17.50.119-1370685416301 (storage id DS-803461661-172.17.50.119-50010-1370681848198) service to localhost/127.0.0.1:9000
java.io.IOException: Incompatible clusterIDs in /usr/hadoop/tmp/dfs/data: namenode clusterID = CID-cd47cf1e-0f81-41b0-97df-7407db9f1fa5; datanode clusterID = CID-0462092f-2740-40a4-bf96-246be2efc49f
        at org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:390)
        at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:190)
        at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:218)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:851)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:822)
        at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:279)
        at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:218)
        at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:661)
        at java.lang.Thread.run(Thread.java:619)

因为每次namenode format会重新创建一个namenodeId,而存放datanode数据的tmp/dfs/data目录下包含了上次format下的id,namenode format清空了namenode下的数据,但是没有清除datanode下的数据,导致启动时失败,所要做的就是每次fotmat前,清空tmp一下 的所有目录.