Namenode 开启HA之后,由于zookeeper异常，出现脑裂现象
执行
$./hdfs haadmin -getServiceState nn1
standby
$./hdfs haadmin -getServiceState nn2
standby
两个互为HA的namenode节点均处于standby 状态，随后执行
$/hdfs haadmin -transitionToActive --forcemanual nn1
强行手工将namenode1状态转换为active
PS： serverID即namenodeID，可以访问http://namenodeip:50070界面查看
Operation category READ is not supported in state standby
原文：https://www.cnblogs.com/felixzh/p/9676696.html