今天配置hbase的時候發現有幾臺機器的regionserver啓不來。報錯如下：
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)
錯誤裏指出節點機的時間和master的時間差距大於30000ms，就是30秒時無法啓動服務。之前hadoop沒有遇到過這個問題，所以hbase存在系統時間同步的問題，並且誤差要再30s以內。
在網上查了一下，要配置服務器時間同步需要用到ntp，最好能連接外網的時間服務器。內網裏面配起來比較麻煩點，所以就手動改了時間，再啓動就可以了。
還有另外一個方案，就是修改hbase最大時間誤差。
在hbase-site.xml添加配置 hbase.master.maxclockskew 180000 Time difference of regionserver from master