Replace node or add node and retire old one?

[ldillon]

Greetings All,
We're running a five node cluster and two of the members are getting old and we want to replace them. Is the "best practice" to, e.g., delete node 2 from the cluster and make a new node 2 and join that to the cluster, or should we add a node #6 and then delete #2?

This question may have been answered, but it's hard to search for because terms like "upgrade" yield results for software upgrades.

 

[mira]

Both are possible. In the case where you add the new nodes first and then remove the old ones, you can keep the VMs running and live-migrate them to the new nodes.
In the other case, if you want your VMs to continue running, you have to make sure your other nodes have enough resources for them to run.

If you want your new nodes to reuse the same IP and name of the old ones, this will be a bit more work in the first case.

 

[ldillon]

Both are possible. In the case where you add the new nodes first and then remove the old ones, you can keep the VMs running and live-migrate them to the new nodes.
In the other case, if you want your VMs to continue running, you have to make sure your other nodes have enough resources for them to run.

If you want your new nodes to reuse the same IP and name of the old ones, this will be a bit more work in the first case.

Mira, Thanks for the reply,

I just finished replacing a node a on a test cluster and it looks like replacing a existing node would work better for me in production.

I ran into issues with the monitor service for Ceph not wanting to start correctly. It appears that the correct thing to do would have been to remove the monitor and OSD's before removing the cluster node.

One more question. On the production side, I need to move the subscription from the old node to the replacement node. I see that there's a Remove Subscription button, but I'm not sure if I can just re-use the subscription key that's in the Subscription window?

Thanks! Larry

 

[mira]

You'll have to reissue the key. This can be done in the shop, or if you have ordered from a partner contact them directly.