[Pacemaker] RHEL/CentOS 6.4: corosync -> CMAN migration

[Michael Schwartzkopff]

Am Sonntag, 10. März 2013, 10:35:33 schrieb Stefan Förster:
> Hello world,
> 
> according to [1] using the pacemaker plugin with corosync is
> deprecated and will cease to be supported at some point in the future
> (on RHEL!). Instead, the use of CMAN and running pacemaker as a
> standalone service is recommended.
> 
> Now, unfortunately, the former (corosync with pcmk plugin) is exactly
> what we are using on two fileservice clusters, so we need a migration
> path with no downtime. I'm going to do some extensive testing later
> this week, but I'd be grateful for a bit of advance help. I think what
> I will try is:
> 
> 1. Put pacemaker into maintenance mode.
> 2. Stop corosync, remove corosync.conf and the config snippet loading
>    pacemaker from within corosync.
> 3. Install cman and ccs.
> 4. Generate new cluster.conf, using appropriate tools.
> 5. Start cman, start pacemaker.
> 
> The two crucial questions are:
> 
> 1. In step (2), will pacemaker stop resources when it's brought down,
>    despite being in maintenance mode?
> 2. In step (5), will the pacemaker resource configuration be
>    preserved throughout this migration?
> 
> Any insights would be greatly appreciated.
> 
> 
> Cheers
> Stefan

Yes. pacemaker should honor the maintanance mode when being stopped or 
started. It also should read the existing configuration from the files.

But if your service is really that crucial be sure to make extended testing 
for the migration on a test system.

Greetings,

Michael Schwartzkopff

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