启动hbase时，hregionserver没有启动的原因

今天配置hbase的时候发现有几台机器的regionserver启不来。报错例如以下：

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)

        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)

        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)

        at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:95)

        at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:79)

        at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:1506)

        at org.apache.hadoop.hbase.regionserver.HRegionServer.tryReportForDuty(HRegionServer.java:1470)

        at org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:563)

        at java.lang.Thread.run(Thread.java:662)

Caused by: org.apache.hadoop.ipc.RemoteException: org.apache.hadoop.hbase.ClockOutOfSyncException: Server s3,60020,1304927875246 has been rejected; Reported time is too far out of sync with master.  Time difference of 41450ms > max allowed of 30000ms

        at org.apache.hadoop.hbase.master.ServerManager.checkClockSkew(ServerManager.java:181)

        at org.apache.hadoop.hbase.master.ServerManager.regionServerStartup(ServerManager.java:129)

        at org.apache.hadoop.hbase.master.HMaster.regionServerStartup(HMaster.java:613)

        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

        at java.lang.reflect.Method.invoke(Method.java:597)

        at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:570)

        at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1039)

at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:771)

        at org.apache.hadoop.hbase.ipc.HBaseRPC$Invoker.invoke(HBaseRPC.java:257)

        at $Proxy5.regionServerStartup(Unknown Source)

at org.apache.hadoop.hbase.regionserver.HRegionServer.reportForDuty(HRegionServer.java:1502)

错误里指出节点机的时间和master的时间差距大于30000ms，就是30秒时无法启动服务。之前hadoop没有遇到过这个问题，所以hbase存在系统时间同步的问题，而且误差要再30s以内。

在网上查了一下。要配置server时间同步须要用到ntp。最好能连接外网的时间server。

内网里面配起来比較麻烦点，所以就手动改了时间。再启动就能够了。

还有另外一个方案，就是改动hbase最大时间误差。

在hbase-site.xml加入配置 hbase.master.maxclockskew 180000 Time difference of regionserver from master