[Pacemaker] Need an idea for dynamic configuration dependng on resource distribution

[Andrew Beekhof]

On Thu, Apr 29, 2010 at 12:15 AM, Andreas Mock <Andreas.Mock at web.de> wrote:
> -----Ursprüngliche Nachricht-----
> Von: Andrew Beekhof <andrew at beekhof.net>
> Gesendet: 27.04.2010 20:56:48
> An: The Pacemaker cluster resource manager <pacemaker at oss.clusterlabs.org>
> Betreff: Re: [Pacemaker] Need an idea for dynamic configuration dependng on resource distribution
>
>>> configuration in the default case (everything o.k.). In this scenario the resources
>>> shall take as much "server estate" as possible.
>>
>>"server estate" == RAM/CPU etc?
>>And you can tell the app how much to use?
>
>
> a) Yes
> b) More or less. Think about mysql with innodb. One central variable is buffer_cache
> which should be "as much as possible". When only one instance is running on a server
> you can make a feasible guess, e.g. 80% of physical mem. As soon as two instances
> are running on on server each instance can only have 80% / 2 of memory for buffer_cache.
> As soon as you "overbook" real memory things go dramatically worse.
>
> Any ideas?

Perhaps add something to the start and stop actions which checks how
many instances are running and fudges the settings accordingly.
Or, maybe you could use a clone with globally-unique=true and pick
which database to start based on the instance number - that way each
instance would get notifications when the other started/stopped.