Manually failing over to the standby NameNode

If you are running a HDFS service with HA enabled, you can manually cause the active NameNode to failover to the standby NameNode. This is useful for planned downtime—for hardware changes, configuration changes, or software upgrades of your primary host.

Go to the HDFS service.
Click the Instances tab.
Click Federation and High Availability.
Locate the row for the Nameservice where you want to fail over the NameNode.
Multiple rows display only when using HDFS federation.
Select Actions > Manual Failover.

note
This option does not appear if HA is not enabled for the cluster.
From the pop-up, select the NameNode that should be made active, then click Manual Failover.

note
For advanced use only: You can set the Force Failover checkbox to force the selected NameNode to be active, irrespective of its state or the other NameNode's state. Forcing a failover will first attempt to failover the selected NameNode to active mode and the other NameNode to standby mode. It will do so even if the selected NameNode is in safe mode. If this fails, it will proceed to transition the selected NameNode to active mode. To avoid having two NameNodes be active, use this only if the other NameNode is either definitely stopped, or can be transitioned to standby mode by the first failover step.
Click Finish.

Cloudera Manager transitions the NameNode you selected to be the active NameNode, and the other NameNode to be the standby NameNode. HDFS should never have two active NameNodes.