ntpdate ntp1.nl.net
hadoop集群要保证各服务器时间一致！不然会报一些错误
Got exception: org.apache.hadoop.yarn.exceptions.YarnException: Unauthorized
request to start container.
This token is expired. current time is
1393504160542 found 1393504069719
原文：http://www.cnblogs.com/jaredyang/p/3572328.html