datanode启动不成功，如下所示，我的136,137.138都是datanode，都启动不了。
查看datanode日志文件发现报错：
一个报错Incompatible clusterIDs in /home/hadoop/data/datanode，需要删除core-site.xml中配置的hadoop.tmp.dir临时目录下的东西。
第二个报错需要删除hdfs-site.xml中配置dfs.datanode.data.dir对应的目录下的东西。
然后重新格式化hdfs后，重启hdfs就可以了。
2019-03-25 08:49:07,753 WARN org.apache.hadoop.hdfs.server.common.Storage: Failed to add storage directory [DISK]file:/home/hadoop/data/datanode/
java.io.IOException: Incompatible clusterIDs in /home/hadoop/data/datanode: namenode clusterID = CID-d034319e-4855-4965-80da-8f18d28e9366; datanode clusterID = CID-462e8968-a7ee-41c6-92ad-504a51f19715
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:1362)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1327)
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:745)
2019-03-25 08:49:07,754 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool <registering> (Datanode Uuid unassigned) service to namenode2/192.168.197.135:8030. 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:1362)
at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:1327)
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:745)