Reduce Ceph cluster to one node?

[Heidegeist]

Hi,

I'm running a 2-node ceph cluster. Before a 3rd node was added, descision has been taken (not by me) to move it all to another platform.
Some VMs have already been moved, some are remaining on the two nodes.

Now I'd like to migrate all remaining VMs to one proxmox-node and remove the then empty 2nd node from the cluster.
Would the remaining single node with ceph work properly?

Thanks and best regards
Andreas

 

[sterzy]

Hi,

Would the remaining single node with ceph work properly?

well, it might "work" but not properly. For Ceph to work properly you need at least three nodes [1]. If you went with the default setting you also have a min size of 2 configured. So if you remove one node now, Ceph will not function at all and you will encounter I/O freezes.

If you have only one node, there really isn't a point to using Ceph. You should switch to something like ZFS.

[1]: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_precondition