[Pacemaker] colocation that doesn't

[Alan Jones]

> Instead of:
>
>  colocation resX-resY -2: resX resY
>
> Try:
>
>  colocation resX-resY -2: resY resX
>

That works fine, as you describe, for placing resY when resX is
limited by the -inf rule; but not the reverse.
In my configuration the -inf constraints come from an external source
and I wish place resX and resY in a symmetric way.
Start with resX and resY which can run on either nodeA or nodeB.
Give each a preferred node respectively; a "weak" preference.
Now request that, if possible, they should run on different nodes;
potentially overriding the "weak" node preference.
Now add external constraints that prohibit one or other from running
on one or the other node.
For example, if any one of the resources is prevented from running on
its preferred node, it should run on the non-preferred node and push
the other resource onto its non-preferred node.
I have not figured out how to express this in pacemaker.
Alan