[ClusterLabs] trace of resource - sometimes restart, sometimes not

[Reid Wahl]

On Thu, Oct 6, 2022 at 4:08 PM Ken Gaillot <kgaillot at redhat.com> wrote:
>
> On Thu, 2022-10-06 at 21:05 +0200, Lentes, Bernd wrote:
> > Hi,
> >
> > i have some problems with our DLM, so i wanted to trace it. Yesterday
> > i just set a trace for "monitor". No restart of DLM afterwards. It
> > went fine as expected.

How did you set a trace just for monitor?

> > I got logs in /var/lib/heartbeat/trace_ra. After some monitor i
> > stopped tracing.
> >
> > Today i set a trace for all operations.
> > Now resource DLM restarted:
> > * Restart    dlm:0                       (             ha-idg-1
> > )   due to resource definition change
> > I didn't expect that so i had some trouble.
> > Is the difference in this behaviour intentional ? If yes, why ? Is
> > there a rule ?
>
> Yes, trace_ra is an agent-defined resource parameter, not a Pacemaker-
> defined meta-attribute. Resources are restarted anytime a parameter
> changes (unless the parameter is set up for reloads).
>
> trace_ra is unusual in that it's supported automatically by the OCF
> shell functions, rather than by the agents directly. That means it's
> not advertised in metadata. Otherwise agents could mark it as
> reloadable, and reload would be a quick no-op.
>
> >
> > Furthermore i'd like to ask where i can find more information about
> > DLM, because it is a mystery for me.

Wish I could help with that -- it's mostly a mystery to me too ;)

> > Sometimes the DLM does not respond to the "monitor", so it needs to
> > be restarted, and therefore all depending resources (which is a lot).
> > This happens under some load (although not completely overwhelmed).
> >
> > Thanks.
> >
> > Bernd
> >
> --
> Ken Gaillot <kgaillot at redhat.com>
>
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-- 
Regards,

Reid Wahl (He/Him)
Senior Software Engineer, Red Hat
RHEL High Availability - Pacemaker