Adding external CEPH node to Proxmox CEPH cluster

[mauro70]

Hi All
maybe a silly question, but so far I haven't found any thread talking about that (maybe because it is silly ): would it be possible to add a non-PVE CEPH node to a CEPH cluster created and managed within a PVE cluster?

Reason:
I have a PVE cluster made by 2 nodes + external quorum device.
I have configured glusterfs in both nodes + an external arbiter only.
I would like to replace glusterfs with ceph, and I have always read that the bare minimum configuration for a stable and reliable CEPH cluster is 3 nodes with a 3/2 configuration. Fair enough, however I cannot afford to purchase a third PVE node to add in the cluster, that's why the idea above.

So, do you think it could be feasible a such configuration? any reason for not doing it?

Thanks in advance for any feedback
Cheers

 

[gurubert]

Funny, I always thought a Ceph node is more expensive because of the additional storage.

 

[mauro70]

Not really, it depends by what you want to achieve.
In any case I'm going to re-use a very old server which is not suitable for PVE (just 16GB of RAM), but which (with debian/ubuntu and an NVME) could be sufficient as third node for ceph.

 

[VictorSTS]

Simplifying, the Ceph performance is determined by the slowest node in the cluster. That very old node may limit your Ceph performance.
That said, simply add that third node to your cluster an use it just to run Ceph services. You have no obligation to run VMs/CTs on it and still get to manage all your Ceph from PVE.

 

[mauro70]

ok, thanks, got your point. I'll do that.
Cheers