[Pacemaker] Manging Virtual Machine's resource

[Lon Hohberger]

On Thu, 2008-05-22 at 00:05 +0800, Xinwei Hu wrote:

> Correct me if I miss understand anything ;)
> 
> a.
> The resource/vm.sh from rgmanager mentioned by Lon is similar to
> resource/Xen from heartbeat.

Yes, they're quite similar right now.


> And agents/xvm from fence, is similar to stonith/external/xen0.

The fencing agent / stonith agents are -very- different, though they
accomplish the same thing.

The xvm agent has not been ported to heartbeat, and I don't think it's
been tested on a cman+openais+pacemaker configuration yet.


> Both are available to pacemaker already.

Not yet.  If you're using pacemaker + STONITH, you should use
stonith/external/xen0 fencing agent and heartbeat's Xen resource-agent
for now.


> b.
> The "inherit" attribute in rgmanager, means the instance of RA
> "inherit" parameters from its
> parent resource. It's a little helpful cause some time we do have to
> double check if the parameters
> passed to different RA are the same.

Correct.


> c.
> I'm looking for a solution to "inherit" RAs.
> Take JeOS for example. We may have different RAs for all different
> kind of JeOS, but all of them are
> only slightly different in a few parameters and monitoring methods. We
> also can have a huge RA to handle
> them all, but that'll be very scary to maintain/evo (i.e Filesystem)

Why not just define a base virtual resource-agent class in your favorite
OO language and write resource agents that inherit from the class?

The RA API is language-agnostic...

Alternatively, there's no reason you can't do a common script and source
it from multiple agents to provide common functionality.  We do it all
the time in rgmanager (heartbeat agents do it too - at least with
ocf-shellfuncs).

I'm not sure this kind of inheritance is something that should be
internal to pacemaker; but others might have differing opinions.

-- Lon