question Re: NameNode HA - Active / Standby Switch - Force them into roles? in Archives of Support Questions (Read Only)

NameNode HA - Active / Standby Switch - Force them into roles?

Eric_Periard — Wed, 08 Jun 2016 19:41:43 GMT

Good day Hortonworks community!

Recently we've went from an extremely old version of Ambari/HDP to the bleeding edge latest edition.

Along the way I just about converted every service that could be made HA into HA.

Now here is an issue I get sometimes regarding to NN and SNN.

Sometimes NN/SNN will both become "Active" or "Standby" namenodes if one or the other crash.

Question: Is there some kind of setting to force them back into static roles when both NameNodes are online instead of having to manually restart the service of another?

Re: NameNode HA - Active / Standby Switch - Force them into roles?

jyadav — Wed, 08 Jun 2016 19:51:09 GMT

@Eric Periard

We don't need to restart any service, you can use below command to force failover.

hdfs haadmin -failover

http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/HDFSCommands.html#haadmin

Re: NameNode HA - Active / Standby Switch - Force them into roles?

Eric_Periard — Wed, 08 Jun 2016 20:35:10 GMT

Very interesting, but it would be nice to have something set them back to Active / Standby automatically once both are online or both have the same status... I have case where both become standby nodes and it breaks access to the hdfs file system.

Re: NameNode HA - Active / Standby Switch - Force them into roles?

jyadav — Wed, 08 Jun 2016 20:54:13 GMT

@Eric Periard

Technically two NN can't be at same status if its happening then either you have configuration issues or hitting some bug.

Re: NameNode HA - Active / Standby Switch - Force them into roles?

Eric_Periard — Wed, 08 Jun 2016 21:06:05 GMT

Most likely the latter.... I haven't been able to figure out what exactly is causing the issue.