[Pacemaker] placement-strategy=minimal - placing and logging

Michael Schwartzkopff ms at sys4.de
Fri Mar 8 02:42:52 EST 2013

Am Donnerstag, 7. März 2013, 21:34:47 schrieb Vladimir:
> Hey everyone,
> ---
> I built up a two node test setup using utilization attributes. In brief
> it consists of:
> node-1: provides cores="4"
> node-2: provides cores="4"
> res-dummy01 requires cores="1"
> res-dummy02 requires cores="2"
> res-dummy03 requires cores="3"
> res-dummy04 requires cores="2"
> ---
> All resources are only able to run if they are distributed in the right
> combination. A working example could like:
> res-dummy01 + res-dummy03 = require 4 cores in sum
> res-dummy02 + res-dummy04 = require 4 cores in sum
> ---
> My goal is to to build up a multi node setup (nodes >= 3). I want to
> use utilization attributes for correct resource distribution since
> cluster resources will require different amount of cpu cores. On os
> level cgroups will restrict system resources. Via placement strategy
> minimal I would like to pack resources on as few nodes as possible so
> one node stays without resources. It should act as a kind of dedicated
> failover node.
> ---
> My issue: basing on the mentioned two node test setup the placing
> strategy only works if the resources a started in the right order, e.g.
> first res-dummy01 than res-dummy03 and so on. If I understood the
> documentation
> (https://github.com/ClusterLabs/pacemaker/blob/master/doc/Pacemaker_Explaine
> d/en-US/Ch-Utilization.txt) correctly "the first eligible node listed in cib
> gets consumed first".
> Is there a possibility to configure it in another way?
> Furthermore if there is a lack of configured cores and thus a resource
> cannot be started I don't see any log messages or crm_mon output.
> Is this the normal behaviour?


as fasr as I understand the utilization feature this is the expected 
behaviour. As beekhof describes in his blog the algorithm is fast but cannot 
resolve the problem completely. Just add more nodes.

You can display the utilisations with the crm_simulate command.

Mit freundlichen Grüßen,

Michael Schwartzkopff

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