question Decommission DataNode Role on NN in Archives of Support Questions (Read Only)

Decommission DataNode Role on NN

DataMike — Fri, 13 Jul 2018 22:09:45 GMT

Hi All, we have a NameNode host that also contains a Datanode role, HBase Region server, Impala Daemon, and Solr Server (see image attached). I am ready to decommission and remove the Datanode role from this host.

Do I need to decommission and remove the Impala, HBase, Solr roles first? (and I guess remove the Resource Manager role as well). Anything else I should be aware of?

Notes: I have already followed the "tuning before decommision" section of this article. We also have 6 other dedicated data nodes. Thank you!

Re: Decommission DataNode Role on NN

bgooley — Fri, 13 Jul 2018 22:21:42 GMT

@DataMike,

You don't have to remove any of the roles you mentioned to decommission the DataNode on this host

HOWEVER, Impala Daemon and Hbase RegionServer roles do not perform as well if they do not have a local DataNode. You may want to remove those roles at some point.

Solr Server I am not certain about.

Resource Manager does not need to be moved.

Re: Decommission DataNode Role on NN

DataMike — Fri, 13 Jul 2018 22:30:49 GMT

Okay thanks @bgooley! So I would just decommision the datanode role first, let it finish, then delete the datanode role - correct? There is about 8TB of data on this node.

Re: Decommission DataNode Role on NN

bgooley — Fri, 13 Jul 2018 22:50:04 GMT

@DataMike,

That should be OK. You can consider what to do with the other roles afterward. Just note that if the impalad or regionserver are used for anything, they will need to read/write to a remote DataNode and they will also be competing with the movement of blocks from the decomissioned dn to a new one.