HBase启动出现org.apache.hadoop.hbase.TableExistsException: hbase:namespace错误

今天在启动HBase的时候莫名的HMaster启动不起来，查看日志后发现这个错误：

2018-09-06 23:05:49,385 FATAL [master:linux201:60000] master.HMaster: Unhandled exception. Starting shutdown.
org.apache.hadoop.hbase.TableExistsException: hbase:namespace
    at org.apache.hadoop.hbase.master.handler.CreateTableHandler.prepare(CreateTableHandler.java:133)
    at org.apache.hadoop.hbase.master.TableNamespaceManager.createNamespaceTable(TableNamespaceManager.java:232)
    at org.apache.hadoop.hbase.master.TableNamespaceManager.start(TableNamespaceManager.java:86)
    at org.apache.hadoop.hbase.master.HMaster.initNamespace(HMaster.java:1046)
    at org.apache.hadoop.hbase.master.HMaster.finishInitialization(HMaster.java:925)
    at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:605)
    at java.lang.Thread.run(Thread.java:748)
2018-09-06 23:05:49,386 INFO  [master:linux201:60000] master.HMaster: Aborting
2018-09-06 23:05:49,387 DEBUG [master:linux201:60000] master.HMaster: Stopping service threads
2018-09-06 23:05:49,387 INFO  [linux201,60000,1536246333803-BalancerChore] balancer.BalancerChore: linux201,60000,1536246333803-BalancerChore exiting
2018-09-06 23:05:49,387 INFO  [master:linux201:60000] ipc.RpcServer: Stopping server on 60000
2018-09-06 23:05:49,387 INFO  [linux201,60000,1536246333803-ClusterStatusChore] balancer.ClusterStatusChore: linux201,60000,1536246333803-ClusterStatusChore exiting
2018-09-06 23:05:49,387 INFO  [CatalogJanitor-linux201:60000] master.CatalogJanitor: CatalogJanitor-linux201:60000 exiting
2018-09-06 23:05:49,389 INFO  [master:linux201:60000.archivedHFileCleaner] cleaner.HFileCleaner: master:linux201:60000.archivedHFileCleaner exiting
2018-09-06 23:05:49,388 INFO  [RpcServer.responder] ipc.RpcServer: RpcServer.responder: stopped
2018-09-06 23:05:49,389 INFO  [RpcServer.responder] ipc.RpcServer: RpcServer.responder: stopping
2018-09-06 23:05:49,388 INFO  [master:linux201:60000] master.HMaster: Stopping infoServer
2018-09-06 23:05:49,387 INFO  [RpcServer.listener,port=60000] ipc.RpcServer: RpcServer.listener,port=60000: stopping
2018-09-06 23:05:49,389 INFO  [master:linux201:60000.oldLogCleaner] cleaner.LogCleaner: master:linux201:60000.oldLogCleaner exiting
2018-09-06 23:05:49,392 INFO  [master:linux201:60000.oldLogCleaner] master.ReplicationLogCleaner: Stopping replicationLogCleaner-0x165af57ee71000b, quorum=linux202:2181,linux201:2181,linux203:2181, baseZNode=/hbase
2018-09-06 23:05:49,405 INFO  [master:linux201:60000.oldLogCleaner] zookeeper.ZooKeeper: Session: 0x165af57ee71000b closed
2018-09-06 23:05:49,408 INFO  [master:linux201:60000-EventThread] zookeeper.ClientCnxn: EventThread shut down
2018-09-06 23:05:49,408 INFO  [master:linux201:60000] mortbay.log: Stopped SelectChannelConnector@0.0.0.0:60010
2018-09-06 23:05:49,420 DEBUG [master:linux201:60000] catalog.CatalogTracker: Stopping catalog tracker org.apache.hadoop.hbase.catalog.CatalogTracker@23a6deb
2018-09-06 23:05:49,421 INFO  [master:linux201:60000] client.HConnectionManager$HConnectionImplementation: Closing zookeeper sessionid=0x165af57ee71000a
2018-09-06 23:05:49,430 INFO  [master:linux201:60000] zookeeper.ZooKeeper: Session: 0x165af57ee71000a closed
2018-09-06 23:05:49,431 INFO  [master:linux201:60000-EventThread] zookeeper.ClientCnxn: EventThread shut down

于是一步步排查问题，首先一般出现HBase启动失败会有以下几个主要的原因：

1、Zookeeper问题，要么是ZK启动出现异常，这时需要检查ZK三个节点进程是否都正常

2、HBase集群之间同步的问题，如果集群之间的节点时间不同步，会导致 regionserver 无法启动，抛出ClockOutOfSyncException 异常，解决办法，将HBase集群之间的时间同步，具体同步自行网上百度，还需要将HBase的hbase-site.xml增加一个属性：hbase.master.maxclockskew 设置更大的值
 

<property>
    <name>hbase.master.maxclockskew</name>
    <value>180000</value>
    <description>Time difference of regionserver from master</description>
</property>

3、再一个就是hadoop集群的问题，也需要去检查集群是否健康

但小编遇到的这个问题比较奇葩，上述的这几个问题都是可以的，集群都健康，时间也都同步了，自己尝试重启了n次都不行，后来经过百度查阅资料，才定位到是zk节点管理冲突的问题，于是便在zk的bin目录下，查看zNode的信息：

执行命令：sh zkCli.sh

查看目录下信息：ls /

将这个节点下的Hbase删除，重启就好了：

rmr /hbase

博客就写到这里，如有问题欢迎指正，晚安了