[Pacemaker] Custom event script during master/slave failover?

[Cal Heldenbrand]

Thanks David!

--Cal

On Fri, Nov 9, 2012 at 4:52 PM, David Vossel <dvossel at redhat.com> wrote:

>
>
> ----- Original Message -----
> > From: "Cal Heldenbrand" <cal at fbsdata.com>
> > To: "The Pacemaker cluster resource manager" <
> pacemaker at oss.clusterlabs.org>
> > Sent: Friday, November 9, 2012 4:29:05 PM
> > Subject: [Pacemaker] Custom event script during master/slave failover?
> >
> >
> > Hi everyone,
> >
> > I'm playing around with the possibility of using Pacemaker in a Redis
> > master/slave cluster. The difficult part of this, is that Redis will
> > not automatically flip itself from read-only slave mode into master
> > mode. A client needs to connect to the slave server and run this
> > SLAVEOF NO ONE command to turn it into a master.
>
> The resource agent should be able to do this. Pacemaker will tell the
> resource agent to promote/demote a resource.  Your Redis agent can then go
> off and do whatever logic is necessary to actually transition the process a
> master/slave process.
>
> >
> > If I set up a master/slave primitive, is it possible to fire an event
> > script during a failover event that would allow me to do this?
> >
> > After the stonith event fires and the broken master reboots,
> > I would
> > write in something special in the Redis init.d script to detect if
> > my peer is already a master, and start up in slave mode.
>
> If you are using Pacemaker, it should be controlling what node has the
> master resource and what node has the slave resource.  Take a look at what
> OCF scripts are and how pacemaker uses them.
>
> >
> > Has anyone else worked up a cluster config with Redis?
>
> Using google, found some work someone did on a redis resource agent.
> https://github.com/martinwalter/resource-agents/blob/master/heartbeat/redis
>
> -- Vossel
> > Thank you,
> >
> > --Cal
> >
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