hadoop启动却发现datanode未启动

跟踪hadoop2.7.2/logs/hadoop-root-datanode-master.log日志文件发现datanode启动失败：

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org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool <registering> (Datanode Uuid unassigned) service to master/192.168.247.192:9000. 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:745)

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之前我每次启动hadoop都会格式化一次，导致namespaceid不一致