[ClusterLabs] question about equal resource distribution
ilia at clearskydata.com
Fri Feb 17 09:43:39 EST 2017
What quantity does pacemaker tries to equalize - number of running resources per node or total stickiness per node?
Suppose I have a bunch of web server groups each with IPaddr and apache resources, and a fewer number of database groups each with IPaddr, postgres and LVM resources.
In that case, does it mean that 3 web server groups are weighted the same as 2 database groups in terms of distribution?
> On Feb 17, 2017, at 2:58 AM, Kristoffer Grönlund <deceiver.g at gmail.com> wrote:
> Ilia Sokolinski <ilia at clearskydata.com> writes:
>> Suppose I have a N node cluster where N > 2 running m*N resources. Resources don’t have preferred nodes, but since resources take RAM and CPU it is important to distribute them equally among the nodes.
>> Will pacemaker do the equal distribution, e.g. m resources per node?
>> If a node fails, will pacemaker redistribute the resources equally too, e.g. m * N/(N-1) per node?
>> I don’t see any settings controlling this behavior in the documentation, but perhaps, pacemaker tries to be “fair” by default.
> Yes, pacemaker tries to allocate resources evenly by default, and will
> move resources when nodes fail in order to maintain that.
> There are several different mechanisms that influence this behaviour:
> * Any placement constraints in general influence where resources are
> * You can set resource-stickiness to a non-zero value which determines
> to which degree Pacemaker prefers to leave resources running where
> they are. The score is in relation to other placement scores, like
> constraint scores etc. This can be set for individual resources or
> globally. 
> * If you have an asymmetrical cluster, resources have to be manually
> allocated to nodes via constraints, see 
> : http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#s-resource-options
> : http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#_asymmetrical_opt_in_clusters
>> Ilia Sokolinski
>> Users mailing list: Users at clusterlabs.org
>> Project Home: http://www.clusterlabs.org
>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>> Bugs: http://bugs.clusterlabs.org
> // Kristoffer Grönlund
> // kgronlund at suse.com
More information about the Users