CDH版 hadoop集群启动报错： java.io.IOException: Incompatible clusterIDs

java.io.IOException: Incompatible clusterIDs in /export/hadoop-2.7.5/hadoopDatas/datanodeDatas2: namenode clusterID = CID-b3356ee2-aaae-4b89-86e2-e6eec8fe6e00; datanode clusterID = CID-c648893d-0a5b-4dc3-ae95-e962e62e0c6c
at org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:775)
at org.apache.hadoop.hdfs.server.datanode.DataStorage.loadStorageDirectory(DataStorage.java:300)
at org.apache.hadoop.hdfs.server.datanode.DataStorage.loadDataStorage(DataStorage.java:416)
at org.apache.hadoop.hdfs.server.datanode.DataStorage.addStorageLocations(DataStorage.java:395)
at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:573)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:1393)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1358)
at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:313)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:216)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:637)
at java.lang.Thread.run(Thread.java:748)
2019-11-04 08:51:21,422 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool <registering> (Datanode Uuid unassigned) service to node01/192.168.100.100:8020. Exiting.
java.io.IOException: All specified directories are failed to load.
at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:574)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:1393)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1358)
at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:313)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:216)
at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:637)
at java.lang.Thread.run(Thread.java:748)

原因：

Hadoop启动后，在使用格式化hdfs namenode -format，会导致datanode和namenode的clusterID不一致

解决办法：

hdfs-site.xml配置文件中 

1.在namenode上， ${dfs.namenode.name.dir}/current/VERSION 里找到clusterID

2. 在出问题的datanode上， ${dfs.namenode.data.dir}/current/VERSION 里找到clusterID, 用步骤1中得到的clusterID覆盖之。

3.重启namenode