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

[Vladislav Bogdanov]

24.10.2016 14:22, Nikhil Utane wrote:
> I had set resource utilization to 1. Even then it scheduled 2 resources.
> Doesn't it honor utilization resources if it doesn't find a free node?

To make utilization work you need to set both:
* node overall capacity (per-node utilization attribute)
* capacity usage by a resource (per-resource utilization attribute)

>
> -Nikhil
>
> On Mon, Oct 24, 2016 at 4:43 PM, Vladislav Bogdanov
> <bubble at hoster-ok.com <mailto:bubble at hoster-ok.com>> wrote:
>
>     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>
>         <mailto: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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