Proxmox/Ceph Cluster with 2 nodes now and a 3rd later?

[anaxagoras]

I'm building my first proxmox cluster and i have 2 of my 3 nodes, the third one should be arriving next month, it's delayed.

Can i set up a cluster and ceph now? and then add the third node once i get it? This will be in my test lab, and not in production until the third node arrives.

I've never used ceph before so i have no clue if it will work.

 

[UdoB]

Can i set up a cluster

Yes. Use a QDevice until you get the third node --> https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_corosync_external_vote_support

and ceph now?

Do not do this. Ceph really needs at least(!) three nodes.

If you implement only two of them you are already degraded. I am not sure if you can "enable" this to work... --> https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_recommendations_for_a_healthy_ceph_cluster

 

[anaxagoras]

I did manage to get this working in a 2/2 configuration on ceph. I'm only using it for testing, but won't go into production until I get all threed nodes. Good news is the new node is arriving today, along with most of the enterprise ssd's.

Instead of a qdevice I edited corosync to give one node 2 votes. Just to mess about with live migration, and performance which so far has been fine for my use case even on the consumer nvme i have on hand now that i'm using for testing while waiting for the enterprise stuff.