It is critical to verify that the NameNode HA infrastructure is functional.
To commission a NameNode HA cluster, we recommend performing explicit tests of vSphere's ability to detect a failed NameNode and to react to that failure. These tests should be performed in addition to any other commissioning tests.
To aid in this commissioning process, the HA monitor RPM includes the Hortonworks Application Monitor (HAM) application. HAM can be used to monitor and restart a remote NameNode. To validate NameNode High Availability, ensure that you follow the instructions as outlined below:
