could only be replicated to 0 nodes instead of minReplication (=1)

Exception in thread “main” org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/ckelsel/test.log could only be replicated to 0 nodes instead of minReplication (=1). There are 0 datanode(s) running and no node(s) are excluded in this operation.

分析日志

2016-02-04 08:48:41,735 WARN org.apache.hadoop.hdfs.server.common.Storage: java.io.IOException: Incompatible clusterIDs in /tmp/hadoop-ckelsel/dfs/data: namenode clusterID = CID-5c919b40-d41f-4201-b6c9-2d58c718acb9; datanode clusterID = CID-0846cd23-9f14-4928-be9c-0d5897a13bdd

2016-02-04 08:48:41,736 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool (Datanode Uuid unassigned) service to localhost/127.0.0.1:9000. Exiting.

java.io.IOException: All specified directories are failed to load.

at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:478)

at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:1338)

at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1304)

at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:314)

at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:226)

at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:867)

at java.lang.Thread.run(Thread.java:745)

2016-02-04 08:48:41,739 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool (Datanode Uuid unassigned) service to localhost/127.0.0.1:9000

2016-02-04 08:48:41,842 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Removed Block pool (Datanode Uuid unassigned)

2016-02-04 08:48:43,842 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Exiting Datanode

2016-02-04 08:48:43,847 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 0

2016-02-04 08:48:43,850 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG:

datanode clusterID 不一致，

因为使用过hadoop-2.7.2 format，现在又使用hadoop-2.6.3

解决方法

hdfs namenode -format -clusterId CID-0846cd23-9f14-4928-be9c-0d5897a13bdd