[ClusterLabs] Antw: [EXT] Preventing a resource from migrating to / starting on a node

[Ken Gaillot]

The use case here is for external code (DRBD) to ban a resource from a
node. While DRBD could add/remove location constraints, it's better to
have permanent (rule-based) location constraints in the configuration,
and let DRBD just set or unset a node attribute to trigger the
constraint.

As a general rule, it's best to avoid automated configuration changes
(via resource agents, crons, DRBD, etc.) other than node attributes.
There's just more room for something to go wrong.

On Tue, 2022-11-29 at 10:50 -0800, Reid Wahl wrote:
> On Tue, Nov 29, 2022 at 7:20 AM Madison Kelly <mkelly at alteeve.com>
> wrote:
> > I was taking Ken's advice. Originally my plan was to use location
> > constraints, but I assume Ken's reasoning was sound for the node
> > attribute approach.
> 
> Location constraints should work for the simple test case you
> presented. There's probably some additional nuance that came up in
> your discussion with Ken. Rules and node attributes can be more
> flexible when the situation is more complex than just "don't run on
> the node with this particular node name".
> 
> > On 2022-11-29 02:51, Ulrich Windl wrote:
> > 
> > Why can't you use a plain location constraint?
> > 
> > Madison Kelly <mkelly at alteeve.com> schrieb am 29.11.2022 um 05:21
> > in Nachricht
> > 
> > 
> > --
> > Madison Kelly
> > Alteeve's Niche!
> > Chief Technical Officer
> > c: +1-647-471-0951
> > https://alteeve.com/
> > 
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> 
-- 
Ken Gaillot <kgaillot at redhat.com>