[ClusterLabs] Antw: Re: Antw: Re: from where does the default value for start/stop op of a resource come ?

Ken Gaillot kgaillot at redhat.com
Wed Aug 2 19:05:18 EDT 2017


On Wed, 2017-08-02 at 18:32 +0200, Lentes, Bernd wrote:
> 
> ----- On Aug 2, 2017, at 10:42 AM, Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de wrote:
> 
> 
> > 
> > I thought the cluster does not perform actions that are not defined in the
> > configuration (e.g. "monitor"). 
> 
> I think the cluster performs and configures automatically start/stop operations if not defined it the resource, 
> but a monitor op has to be configured explicitly, to my knowledge.

Correct. We've considered adding an implicit monitor if none is
explicitly specified, as well as adding implicit master and slave role
monitors if only one monitor is specified for a master/slave resource.
That might happen in a future version.

> >> 2. Set timeouts for any operations that have defaults in the RA
> >>    meta-data?
> >> 
> >> What most people seem to expect is 2), but it sounds like what you are
> >> expecting is 1). Crmsh can't read minds, so it would have to pick one or
> >> the other.
> 
> Yes, i expected the cluster chooses the "defaults" from the meta-data of the RA..

It is confusing. Pacemaker doesn't use much from the resource agent
meta-data currently. I could see an argument for using the RA defaults,
though it could still be confusing since there are multiple possible
interpretations.

The implementation would be complicated, though. Currently, only the
crmd has the meta-data information; it's not in the CIB, so the policy
engine (which sets the timeouts) doesn't have it. Also, we can schedule
probe, start, and monitor operations in a single transition, before
we've gotten the RA meta-data, so the timeouts couldn't be known when
the actions are scheduled. There are potential ways around that, but it
would be a significant project.

> >> Another thing to consider is that if RA meta-data is preferred over the
> >> global default timeout, then the global default timeout wouldn't be used
> >> at all for operations that happen to have default timeouts in the
> >> meta-data. That seems surprising as well to me.
> 
> Yes. You configure global defaults, but they are not used. Confusing.
> 
> Bernd
>  
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