On 2011-07-11 13:40, Ulrich Windl wrote: > Hi! > > I think I misunderstood "colocation": I thought a colocation means if two > resources are running, the should be (or not) on the same node. > In practive however, there seems to be more: > I have two resources, say A and B. A has highter priority than B, and an > ordering that B should be started after A. As B depends on resources provided > by A, I also added a infnity colocation for A and B. > Now I'm surprised that when I tell CRM to stop B, B is stopped, but A also.
It would be helpful if you shared your configuration, rather than
paraphrased it. That way we could have figured out if your configuration
actually matches the blurb you posted.
It is non-obvious, from your description, how you set a "higher
priority" for one resource over another, whether your order constraint
is advisory or mandatory, how you placed your colocation constraint, etc.
> I wanted B to be more independent of A compared to putting A and B into one
> group.
>
> What did I misunderstand?
You probably (I'm guessing) missed the fact that colocation constraints
are directional. They are not reversible at will.
If you have a colocation constraint like
inf: foo bar
... then verbalize this as "foo on bar". foo must always run "on bar",
that is to say, on whichever node is currently managing bar. What this
implies is that if bar isn't running anywhere, foo can't run, either. By
contrast if foo can't run anywhere, then bar is unaffected.
> IMHO: colocation should not affect the running state of resources: If A and B
> should have a infinity colocation, that constraint should be still fulfilled
> if only one of both (A, B) is running. Specifically "colocation" is not a
> symmetrical version of "depends_on" ("requires")
Can you please stop broadcasting your own opinion before you establish
the facts and/or understand the underlying concepts? Or is your opinion
set in stone already, and facts would merely confuse you?
Florian
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