hadoop从机datanode 启动失败，日志错误：java.io.IOException: Incompatible clusterIDs，Initialization failed for Bl

当群起Hadoop集群时候，发现两台从机的datanode启动都是失败的状态，查看日志发现，错误信息是：
2019-06-20 09:53:12,874 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Block pool (Datanode Uuid unassigned) service to hadoop102/192.168.31.102:9000 starting to offer service
2019-06-20 09:53:12,884 INFO org.apache.hadoop.ipc.Server: IPC Server Responder: starting
2019-06-20 09:53:12,886 INFO org.apache.hadoop.ipc.Server: IPC Server listener on 50020: starting
2019-06-20 09:53:13,354 INFO org.apache.hadoop.hdfs.server.common.Storage:
Lock on /opt/module/hadoop-2.7.2/data/tmp/dfs/data/in_use.lock acquired by nodename 8824@hadoop103
2019-06-20 09:53:13,356 WARN org.apache.hadoop.hdfs.server.common.Storage:
java.io.IOException: Incompatible clusterIDs in /opt/module/hadoop-2.7.2/data/tmp/dfs/data: namenode clusterID = CID-ca1a2572-90d0-457d-a9f1-c76ad99a0d30;
datanode clusterID = CID-3c0a4faa-c5b1-4942-96f7-5f5186e5152a
2019-06-20 09:53:13,356 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode:
Initialization failed for Block pool (Datanode Uuid unassigned) service to hadoop102/192.168.31.102:9000. 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:1358)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1323)
at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:317)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:223)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:802)
at java.lang.Thread.run(Thread.java:748)
2019-06-20 09:53:13,357 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool (Datanode Uuid unassigned) service to hadoop102/192.168.31.102:9000
2019-06-20 09:53:13,474 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Removed Block pool (Datanode Uuid unassigned)
2019-06-20 09:53:15,475 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Exiting Datanode
2019-06-20 09:53:15,477 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 0
2019-06-20 09:53:15,479 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down DataNode at hadoop103/192.168.31.103
************************************************************/

如上，Incompatible clusterIDs in /opt/module/hadoop-2.7.2/data/tmp/dfs/data: namenode clusterID = CID-ca1a2572-90d0-457d-a9f1-c76ad99a0d30;
datanode clusterID = CID-3c0a4faa-c5b1-4942-96f7-5f5186e5152a，
就是namenode 的cluster_id 与datanode的cluster_id 不符合，根据日志，去从机/opt/module/hadoop-2.7.2/data/tmp/dfs/data的位置 改成与namanode一致，再启动就好了。