[DRBD-user] Running Different Versions of drbd / kmod-drbd on different nodes

[Roland Kammerer]

On Tue, May 24, 2022 at 04:43:18PM +0000, Eric Robinson wrote:
> If a cluster has 4 data nodes, and they are deployed in such a way
> that Nodes 1 & 2 replicate only to each other, and Nodes 3 & 4
> replicate only to each other, is it okay to run Nodes 1 & 2 on a
> different version of drbd and kmod-drbd than nodes 3 & 4?

Should be fine in general. I mean what if you upgrade nodes, and you
upgrade 1 and then reconnect, then you also have 2 different versions.
And that is a of course a supported upgrade scenario.  And in your case
they don't even talk to each other. Anyways, when a resource connects to
a peer there is a handshake and there min and max protocol versions get
exchanged and as long as they have some common ground the connection
get's established, otherwise aborted. Fun fact: there is current work
that latest DRBD9 can even talk to 8.4 again.

Regards, rck