[ClusterLabs] Pacemaker and Corosync versions compatibility

[Digimer]

On 24/06/16 09:46 PM, Maciej Kopczyński wrote:
> Hello,
> 
> I've been following a tutorial to set up a simple HA cluster using
> Pacemaker and Corosync on CentOS 6.x while I have noticed that in the
> original documentation it is stated that:
> 
> "Since |pcs| has the ability to manage all aspects of the cluster (both
> corosync and pacemaker), it requires a specific cluster stack to be in
> use: corosync 2.0 or later with votequorum plus Pacemaker 1.1.8 or later."
> 
> Here are the versions of packages installed in my system (CentOS 6.7):
> pacemaker-1.1.14-8.el6.x86_64
> corosync-1.4.7-5.el6.x86_64
> 
> I did not do that much of testing, but my cluster seems to be more or
> less working so far, what are the compatibility issues then? What will
> not work with corosync in version lower than 2.0?
> 
> Thanks in advance for your answers.

You will notice on EL6 that you have cman installed and that there is an
/etc/cluster/cluster.conf file. This is a special plugin setup made to
provide support for pacemaker in RHEL 6 (was added officially in late
6.4/6.5 release). This is the quorum provider and it manages corosync
v1.4 so that pacemaker can work with it.

This is odd, admittedly, but it was part of the process of merging what
had formerly been two separate HA stacks. You can read about the history
and merger here: https://alteeve.ca/w/History_of_HA_Clustering

In RHEL 7, the merger was finished and you have the final stack of just
corosync v2 and pacemaker. However, in el6 with the cman plugin, it will
also work just fine.

-- 
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?