[SOLVED] Ambari There are no DataNodes to do rolling restarts when there are DataNodes that do need a restart

When maintaining a Hadoop cluster, you will need to restart various service from time-to-time when/if you update Hadoop configurations.

I ran into a problem today with Ambari where I wanted to do a rollling restart of all of my DataNodes, but when I clicked on the “Restart DataNodes” entry in the “Restart” drop down the dialog indicated “There are no DataNodes to do rolling restarts”.

ambari_qa_incorrect_dn_restart_dialog.png

This was clearly incorrect.

ambari_qa_datanode_restart_alert.png

It did not take me too long to figure out that I had already put HDFS into Maintenance Mode.  As a result, Ambari does not see that there are any DataNodes that need to be restarted.

Taking HDFS out of Maintenance mode allowed me to then execute a rolling restart through Ambari.

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