[ClusterLabs] why and when a call of crm_attribute can be delayed ?

[Jehan-Guillaume de Rorthais]

Le Sat, 7 May 2016 00:27:04 +0200,
Jehan-Guillaume de Rorthais <jgdr at dalibo.com> a écrit :

> Le Wed, 4 May 2016 09:55:34 -0500,
> Ken Gaillot <kgaillot at redhat.com> a écrit :
...
> > There would be no point in the pre-promote notify waiting for the
> > attribute value to be retrievable, because the cluster isn't going to
> > wait for the pre-promote notify to finish before calling promote.
> 
> Oh, this is surprising. I thought the pseudo action
> "*_confirmed-pre_notify_demote_0" in the transition graph was a wait for each
> resource clone return code before going on with the transition. The graph is
> confusing, if the cluster isn't going to wait for the pre-promote notify to
> finish before calling promote, I suppose some arrows should point directly
> from start (or post-start-notify?) action directly to the promote action
> then, isn't it?
> 
> This is quite worrying as our RA rely a lot on notifications. As instance, we
> try to recover a PostgreSQL instance during pre-start or pre-demote if we
> detect a recover action...

I'm coming back on this point.

Looking at this documentation page:
http://clusterlabs.org/doc/en-US/Pacemaker/1.1/html/Pacemaker_Explained/s-config-testing-changes.html

I can read "Arrows indicate ordering dependencies".

Looking at the transition graph I am studying (see attachment, a simple
master resource move), I still don't understand how the cluster isn't going to
wait for a pre-promote notify to finish before calling promote.

So either I misunderstood your words or I miss something else important, which
is quite possible as I am fairly new to this word. Anyway, I try to make a
RA as robust as possible and any lights/docs are welcome!

Regards,
-- 
Jehan-Guillaume de Rorthais
Dalibo
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