Kurt && Hadoop && Spark

使用start-all.sh常會發現DataNode消失
登入log來debug發下以下訊息

java.io.IOException: Incompatible clusterIDs in /opt/hadoop/tmp/dfs/data: namenode clusterID = CID-63c1c251-ea21-4d2e-86ee-268a588dcd3e; datanode clusterID = CID-ef21daea-d77e-4210-a957-21efdf4c133a
	at org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:391)
	at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:191)
	at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:219)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:837)
	at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:808)
	at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:280)
	at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:222)
	at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:664)
	at java.lang.Thread.run(Thread.java:745)


似乎是/tmp資料夾裡的舊ID和新ID不相容 
解決辦法就是移除/opt/hadoop/tmp 再次format namenode