[ClusterLabs] Corosync 2 vs Corosync 3

[Ken Gaillot]

On Mon, 2021-10-25 at 13:44 +0000, Toby Haynes wrote:
> Looking at Pacemaker 2.1, I see that both corosync 2 and corosync 3
> are supported. The last corosync 2 release (2.4.5) came out in 30
> July 2019. Will there come a point when a future Pacemaker release
> might only support the Corosync 3 (or later) series?

There's nothing that Pacemaker has to do specially for Corosync 2 vs 3,
so it's unlikely support will ever be dropped for just 2. Of course
everything changes eventually, but nothing's on the horizon.

If you're choosing between the two, keep in mind Corosync 3 doesn't
support rolling upgrades from 2, even though Pacemaker itself doesn't
care.

> Are there good use cases today where Corosync 2 is a better choice?

Not that I know of. I'd only use it when it's what the OS provides.
There are a few features only supported by 2 (like node discovery via
multicast), but I don't think they're worth staying on 2.

> Thanks,
>  
> Toby Haynes
-- 
Ken Gaillot <kgaillot at redhat.com>