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Re: [Linux-cluster] heartbeat to rgmanager design question

On Thu, Nov 27, 2008 at 15:57, Brian Kroth <bpkroth gmail com> wrote:
> Hello all,
> I've been using Heartbeat in past to do resource failover with the
> following scheme:
> 1) Each node in the cluster runs a dummy monitoring resource agent as a
> clone.  This resource agent monitors the health of a service on the node
> using whatever rules one wants to write into it.  For instance, make
> sure the service is not in maintenance mode, mysql is running, queries
> return timely, and replication is up to date.  If all the checks pass it
> uses attrd_updater to set an attribute for that service on the node to
> 1.  Else, it is set to 0.  Note that this resource agent in no way
> affects the service it is monitoring.
> 2) The cluster configuration uses the attributes for each of the
> monitored services to generate a score for the machine.  The machine
> with the highest score gets to host the virtual ip for that service.
> This scheme allows one to, for instance, touch a file on a machine that
> will signify that it's in maintenance mode.  The service ip would then
> be moved to another node, leaving one to test out the service on the
> machine's management ip without removing it from the cluster itself
> which would cause a lack of gfs access.  It also provides for more
> granular monitoring of each service.
> I want to know how I would configure rgmanager with something similar to
> this - to have resource agents that continually monitor the status of a
> service on each node and then move service IPs accordingly.

Just out of interest, where did the rgmanager requirement come from?

The Heartbeat resource manager also runs on OpenAIS now which, IIRC,
is what rgmanager uses... so, in theory, it can manage anything
rgmanager can.

> I see that one can write their own agents, but I don't see a scoring
> scheme anywhere.  My concern is that if I simply write an agent to
> monitor a service and have an ip depend upon the return code of that
> monitoring agent the service would not ever be failed back to the
> original host.
> Does this make sense?
> Thanks,
> Brian
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