Why hbase need to sync time between servers?

[周文辉]

I installed hbase in my hadoop cluster.
when i started hbase and i got an exception about
ClockOutOfSyncException, somthing like this:

org.apache.hadoop.hbase.ClockOutOfSyncException:
org.apache.hadoop.hbase.ClockOutOfSyncException:
Server slave,60020,1310983722679 has been rejected; Reported time is
too far out of sync with
master.  Time difference of 33514ms > max allowed of 30000ms

I know i need to sync the time.

But does anybody know why hbase need this sync?

Thanks very much!