[ClusterLabs] Antw: Re: Antw: Unexpected Resource movement after failover

[Vladislav Bogdanov]

24.10.2016 14:04, Nikhil Utane wrote:
> That is what happened here :(.
> When 2 nodes went down, two resources got scheduled on single node.
> Isn't there any way to stop this from happening. Colocation constraint
> is not helping.

If it is ok to have some instances not running in such outage cases, you 
can limit them to 1-per-node with utilization attributes (as was 
suggested earlier). Then, when nodes return, resource instances will 
return with (and on!) them.


>
> -Regards
> Nikhil
>
> On Sat, Oct 22, 2016 at 12:57 AM, Vladislav Bogdanov
> <bubble at hoster-ok.com <mailto:bubble at hoster-ok.com>> wrote:
>
>     21.10.2016 19:34, Andrei Borzenkov wrote:
>
>         14.10.2016 10:39, Vladislav Bogdanov пишет:
>
>
>             use of utilization (balanced strategy) has one caveat:
>             resources are
>             not moved just because of utilization of one node is less,
>             when nodes
>             have the same allocation score for the resource. So, after the
>             simultaneus outage of two nodes in a 5-node cluster, it may
>             appear
>             that one node runs two resources and two recovered nodes run
>             nothing.
>
>
>         I call this a feature. Every resource move potentially means service
>         outage, so it should not happen without explicit action.
>
>
>     In a case I describe that moves could be easily prevented by using
>     stickiness (it increases allocation score on a current node).
>     The issue is that it is impossible to "re-balance" resources in
>     time-frames when stickiness is zero (over-night maintenance window).
>
>
>
>             Original 'utilization' strategy only limits resource
>             placement, it is
>             not considered when choosing a node for a resource.
>
>
>
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