[ClusterLabs] resource management of standby node

[Ken Gaillot]

On Wed, 2020-12-09 at 10:57 +0800, Roger Zhou wrote:
> On 12/1/20 4:03 PM, Ulrich Windl wrote:
> > > > > Ken Gaillot <kgaillot at redhat.com> schrieb am 30.11.2020 um
> > > > > 19:52 in Nachricht
> > 
> > <f3c9daaca84fea2c0db99c5ae161e4785e75a802.camel at redhat.com>:
> > 
> > ...
> > > 
> > > Though there's nothing wrong with putting all nodes in standby.
> > > Another
> > > alternative would be to set the stop-all-resources cluster
> > > property.
> > 
> > Hi Ken,
> > 
> > thanks for the valuable feedback!
> > 
> > I was looking for that, but unfortunately crm shell cannot set that
> > from the resource (or node) context; only from the configure
> > context.
> > I don't know what a good syntax would be "resource stop all" /
> > "resource start all" or "resource stop-all" / "resource unstop-all"
> > (the asymmetry is that after a "stop all" you cannot start a singly
> > resource (I guess), but you'll have to use "start-all" (which, in
> > turn, does not start resources that have a stopped role (I guess).
> > 
> > So maybe "resource set stop-all" / "resource unset stop-all" /
> > "resource clear stop-all"
> > 
> 
> 1.
> Well, let `crm resource stop|start all` change the cluster property
> of 
> `stop-all-resources` might contaminate the syntax at the resources
> level alone. 
> To avoid that, the user interface need be more carefully to deliver
> the proper 
> information at the first place about the internals at some degree to
> avoid the 
> potential misunderstanding or questions.
> 
> 2.
> On the other hand, people might naturally read `crm resource stop
> all` as 
> changing all resources `target-role=Stopped`. Well, technically this
> seems a 
> bit awkward, but no obvious benefit comparing to stop-all-resources.
> And, 
> pacemaker developers could comment more internals around this.

You can set target-role to Stopped in resource defaults, and the
difference compared to stop-all-resources is that stop-all-resources
would take precedence over any target-role set on a specific resource,
while the resource default would not.

Setting target-role to Stopped on every resource individually would be
the same as setting stop-all-resources, just more painful. :)

> 3.
> `resource set|unset` add more commands under `resource` and will
> confuse some 
> users and should be avoided in my view.
> 
> I feel more discussion is expected, though my gut feeling approach 1
> is a 
> better one.
> 
> Anyway, good topic indeed. Feedback from more users would be useful
> to shape 
> the better UI/UX. I can imagine some people may have idea to suggest
> "--all" 
> even, btw.
> 
> Thanks,
> Roger
> 
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-- 
Ken Gaillot <kgaillot at redhat.com>