[ClusterLabs] compatibility between Corosync 1.4.7 and 2.4.0

[Ken Gaillot]

On Thu, 2018-10-04 at 08:51 +0200, Jan Friesse wrote:
> Ramasubramanian,
> 
> > Hi Team,
> > We are doing an upgrade of corosync to 2.4.0 and would like to know
> > if that is compatible with 1.4.7. The reason is that one node in
> > the cluster will be 1.47 during the upgrade.Let me know.
> 
> No, Corosync 1.x and 2.x are not wire compatible. Configs usually
> are. I 
> would recommend to turn off the 1.4.7 node as long as it's not using 
> crypto because messages sent by that node may crash 2.4.0 corosync 
> (fixed in 2.4.4)
> 
> Regards,
>    Honza
> 
> > Thanks,Venkat

If this is a pacemaker cluster, you can follow the detach-and-reattach
upgrade method to upgrade corosync without affecting running cluster
services:

http://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/1.1/html-single/Pa
cemaker_Explained/index.html#_detach_and_reattach

If this is part of a wider OS upgrade, which will require a reboot,
then that will not be an option.
-- 
Ken Gaillot <kgaillot at redhat.com>