Upgrading cluster 4 to 6. Several questions with CEPH.

[panther-ra]

Hello all!
I have a 3 node cluster on old 4.4 release, also its have a CEPH inside a cluster.
Its not possible upgrade it step by step, with zero downtime.
So i decided create new Proxmox server on 6 release, but it not compatible with old versions.
First question - it is possible install and configure standalone CEPH storage and restore on it backups of VMs, later i will add other nodes.
Second - will cluster work with only 2 nodes?
My plan is install and configure new instance of Proxmox 6 with CEPH, restore on it backups of VMs.
Then add second one node to new instance, make a cluster, restore vms, and do it on 3 node.
My goal upgrade cluster from 4 to 6 version with fresh install on all nodes.

 

[Alwin]

First question - it is possible install and configure standalone CEPH storage and restore on it backups of VMs, later i will add other nodes.

While possible, it is not recommended, as you risk loosing data.

Second - will cluster work with only 2 nodes?

Yes, but it will be degraded and any additional failure will result in a read-only pool.

My goal upgrade cluster from 4 to 6 version with fresh install on all nodes.

You can do this or follow the upgrade guides from PVE 5.x (Ceph Luminous) and PVE 6.x (Ceph Nautilus), one after the other. There is no down time needed.

1. https://pve.proxmox.com/wiki/Upgrade_from_4.x_to_5.0
2. https://pve.proxmox.com/wiki/Upgrade_from_5.x_to_6.0