[Pacemaker] General question about pacemaker

[Florian Haas]

On Sun, Jun 10, 2012 at 3:07 PM, "Stefan Günther" <smguenther at web.de> wrote:
>
> Hello,
>
> I have a general question about the features of pacemaker.
>
> We are planning to setup a HA solution with pacemaker, corosync and drbd.
>
> After a failure of the master at later its recovery, drbd will sync the
> data from the slave to the master.
>
> Is it now possible to configure pacemaker and/or corosync to perform a
> failback, AFTER drbd has finished syncing?

Yes.

> And if yes, which componenten is responsible for waiting from the signal
> from drbd that syncing has finished?

The ocf:linbit:drbd resource agent (the Pacemaker resource agent that
ships with DRBD) influences the resource master score, which Pacemaker
evaluates for the placement of the DRBD Master role among cluster
nodes. You can combine this with a location contraint that sets a
preference for one of your nodes as the DRBD Master (Primary). If you
set your location constraint score correctly, you would get the
behavior you want.

However, why do you want automatic failback? If your cluster nodes are
interchangeable in terms of performance, you shouldn't need to care
which node is the master. In other words the concept of having a
"preferred master" is normally moot in well-designed clusters.

Hope this is useful.

Cheers,
Florian

--
Need help with High Availability?
http://www.hastexo.com/now