On Mon, Mar 19, 2018 at 5:19 AM, Joseph Kelly <Joseph.Kelly@tradingscreen.com> wrote:

Sorry to ask again, But I can see from the link below the that nodes and engines should work between minor number

upgrades.

Indeed.

But is ovirt 4.2.x backward compatible with, say, 3.6 nodes. Does anyone know ? Is this documented anywhere ?

You can search the release notes pages of 4.2.z releases for '3.6' to find relevant bugs.

Just _using_ such hosts, should work.

Adding a 3.6 host to a 4.2 engine will likely break.

It's definitely not intended to be used for long times - you are encouraged to upgrade your hosts too, soon after the engine.

If you plan a very long transition period, I suggest to create a list of operations you might want/need to do, and test everything in a test environment.

[ovirt-users] compatibility relationship between datacenter, ovirt and cluster

https://www.mail-archive.com/users@ovirt.org/msg17092.html

Thanks,
Joe.

From: Joseph Kelly
Sent: Wednesday, March 14, 2018 5:32 PM
To: users@ovirt.org
Subject: Query about running ovirt-4.2.1 engine support 3.x nodes ?

Hello All,

I have two hopefully easy questions regarding an ovirt-4.2.1 engine support and 3.x nodes ?

1) Does an ovirt-4.2.x engine support 3.x nodes ? As This page states:

"The cluster compatibility is set according to the version of the least capable host operating system in the cluster."

https://www.ovirt.org/documentation/upgrade-guide/chap-Post-Upgrade_Tasks/

Which seems to indicate that you can run say a 4.2.1 engine with lower version nodes, but is that correct ?

2) And can you just upgrade the nodes directly from 3.x to 4.2.x as per these steps ?

1. Move the node to maintenance
2. Add 4.2.x repos
3. yum update
4. reboot
5. Activate (exit maintenance)

This should work. You can also use the admin web ui for updates, which might be better, didn't check recently. See also e.g.:

https://bugzilla.redhat.com/show_bug.cgi?id=1344020

Best regards,

Didi