[Pacemaker] Suggestions/questions for Pacemaker

Andrew Beekhof andrew at beekhof.net
Fri Nov 6 06:56:40 EST 2009

On Fri, Nov 6, 2009 at 12:16 PM, Colin <colin.hch at gmail.com> wrote:
> Hi All,
> we are really happy with Pacemaker because we can already express a
> lot of what we need in the configuration, and so far it has been
> performing really well! There are some areas beyond the basics where
> our usage of the cluster suggests some directions for further
> extensions that I would like to put up for discussion -- also because
> some of the issues might already be solved/solvable, or be due to us
> not using the best method to achieve something...
> 1) Some of our resources take a long time to start or stop; AFAICS
> from crm_mon, the cluster only knows, or at least: only shows, the
> states "Started" and "Stopped"; it would be nice to see a "Starting",
> "Migrating from/to xxx" and "Stopping" in crm_mon while the RA script
> is running with the corresponding action.

This is already somewhat possible.  There is an option to turn on
these intermediate states which I think the GUI can take advantage of.
It not enabled by default because of the additional messaging overhead
it creates.

> 2) If I haven't missed something, there is no possibility to configure
> dependencies on "any of a group"; given a configuration of "resource
> set A has resources A1, A2, ..., An", we would like to say that
> "resource B needs at least any n resources from group A
> up-and-running, and it would be good if they were all up-and-running."
> (The latter is of course already possible with an appropritate
> advisory ordering constraint.)

Nod.  http://developerbugs.linux-foundation.org/show_bug.cgi?id=2007

> 3) In order to recover better from [human] error, is there a
> possibility to tell the cluster to _always_ monitor all resources on
> all nodes (rather than only the resources that should be running on
> any given node)? If not...

Well its possible in theory, we've not had much demand for such a
feature though.

> 4) Invoking "crm_node -q" yields a text with the result; it would be
> nice to have the result in the return code, too.

good point

> (5) The subject of [cluster] resource constaints based on
> [cpu/memory/net/i/o] resource consumption is already being discussed
> on this list.)
> 6) The "multiple-active" parameter is documented as having three
> choices, "block" -> do nothing and mark as unmanaged, "stop_only" ->
> stop all instances, "stop_start" -> stop all instances and then start
> one; the first thing that I wanted to configure, but doesn't exist, is
> 'stop all except one instance'.

generally thats not considered safe.
and such a condition should be a very rare occurrence.

> 7) The naming convention for the XML config seems more difficult than
> necessary with the mixed use of underscores and dashes as
> word-separators.

most of the underscores were replaced by dashes with 1.0, the only
underscores that remain were ones we couldn't change for compatibility

thanks for your feedback!

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