Hadoop集群手动主备切换

 查看节点状态

#查看节点状态
[root@hadoop1 bin]# hdfs haadmin -getServiceState nn1
standby
[root@hadoop1 bin]# hdfs haadmin -getServiceState nn2
active
[root@hadoop1 bin]# pwd
/root/tools/hadoop/tools/hadoop/bin

将 NN2 切换为 Standby 备用节点

hdfs haadmin -transitionToStandby --forcemanual nn2

将 NN1 切换为 Active 备用节点

hdfs haadmin -transitionToActive --forcemanual nn1

[root@hadoop1 bin]# hdfs haadmin -transitionToStandby --forcemanual nn2
You have specified the --forcemanual flag. This flag is dangerous, as it can induce a split-brain scenario that WILL CORRUPT your HDFS namespace, possibly irrecoverably.

It is recommended not to use this flag, but instead to shut down the cluster and disable automatic failover if you prefer to manually manage your HA state.

You may abort safely by answering 'n' or hitting ^C now.

Are you sure you want to continue? (Y or N) Y
23/04/19 17:19:02 WARN ha.HAAdmin: Proceeding with manual HA state management even though
automatic failover is enabled for NameNode at hadoop2/192.168.1.202:9000
[root@hadoop1 bin]# hdfs haadmin -getServiceState nn2
standby
[root@hadoop1 bin]# hdfs haadmin -transitionToActive --forcemanual nn1
You have specified the --forcemanual flag. This flag is dangerous, as it can induce a split-brain scenario that WILL CORRUPT your HDFS namespace, possibly irrecoverably.

It is recommended not to use this flag, but instead to shut down the cluster and disable automatic failover if you prefer to manually manage your HA state.

You may abort safely by answering 'n' or hitting ^C now.

Are you sure you want to continue? (Y or N) Y
23/04/19 17:20:35 WARN ha.HAAdmin: Proceeding with manual HA state management even though
automatic failover is enabled for NameNode at hadoop2/192.168.1.202:9000
23/04/19 17:20:35 WARN ha.HAAdmin: Proceeding with manual HA state management even though
automatic failover is enabled for NameNode at hadoop1/192.168.1.201:9000

切换后的状态及效果图

[root@hadoop1 bin]# hdfs haadmin -getServiceState nn2
standby
[root@hadoop1 bin]# hdfs haadmin -getServiceState nn1
active