Ken Gaillot <kgail...@redhat.com> writes: > On 03/30/2016 08:37 PM, Ferenc Wágner wrote: > >> I've got a couple of resources (A, B, C, D, ... more than cluster nodes) >> that I want to spread out to different nodes as much as possible. They >> are all the same, there's no distinguished one amongst them. I tried >> >> <rsc_colocation id="cl-test-spread" score="-50"> >> <resource_set id="cl-test-spread-set" sequential="false"> >> <resource_ref id="A"/> >> <resource_ref id="B"/> >> <resource_ref id="C"/> >> <resource_ref id="D"/> >> </resource_set> >> <resource_set id-ref="cl-test-spread-set"/> >> </rsc_colocation> >> >> But crm_simulate did not finish with the above in the CIB. >> What's a good way to get this working? > > Per the docs, "A colocated set with sequential=false makes sense only if > there is another set in the constraint. Otherwise, the constraint has no > effect." Using sequential=false would allow another set to depend on all > these resources, without them depending on each other.
That was the very idea behind the above colocation constraint: it contains the same group twice. Yeah, it's somewhat contrived, but I had no other idea with any chance of success. And this one failed as well. > I haven't actually tried resource sets with negative scores, so I'm not > sure what happens there. With sequential=true, I'd guess that each > resource would avoid the resource listed before it, but not necessarily > any of the others. Probably, but that isn't what I'm after. > By default, pacemaker does spread things out as evenly as possible, so I > don't think anything special is needed. Yes, but only on the scale of all resources. And I've also got a hundred independent ones, which wash out this global spreading effect if you consider only a select handful. > If you want more control over the assignment, you can look into > placement strategies: We use balanced placement to account for the different memory requirements of the various resources globally. It would be possible to introduce a new, artifical utilization "dimension" for each resource group we want to spread independently, but this doesn't sound very compelling. For sets of two resources, a simple negative colocation constraint works very well; it'd be a pity if it wasn't possible to extend this concept to larger sets. -- Thanks, Feri _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org