5.x to 6.x Hybrid upgrade possible?

[e100]

During the upgrade process I have some nodes that I would like to reinstall rather then do a dist-upgrade to 6.x.

Is it possible to do this?:

1. Upgrade Corosync to new version in 5.x cluster
2. Upgrade some but not all 5.x to 6.x using dist-upgrade
3. Delete a 5.x node from the cluster
4. Do fresh install of 6.x on deleted node
5. Join reinstalled 6.x node to cluster
6. Live Migrate VMs to the reinstalled 6.x node.
7. Return to step 2 until all nodes are running 6.x

 

[mira]

That should be possible if you're first upgrading all nodes you want to upgrade and then deleting the remaining PVE5 nodes you want to reinstall.
Always make backups! And you could test your scenario in a virtual cluster beforehand. (create some VMs, join them to a cluster, and go through all your planned steps)

 

[e100]

So basically we cannot add new 6.x nodes until the cluster only contains 6.x nodes.

 

[spirit]

So basically we cannot add new 6.x nodes until the cluster only contains 6.x nodes.

no it's possible, just not recommend to keep mixed cluster too long. (but from corosync view, if you have corosync 3.X on proxmox5, it should be ok).