[Linux-cluster] Resource placement after node comes online.

Vallevand, Mark K Mark.Vallevand at UNISYS.com
Thu Oct 1 17:17:17 UTC 2015

Thank you.

As a mind-experiment, consider this very simple example.  Is my understanding correct?

3 node cluster.  All node equal with capacity 10.  Total cluster capacity 30.
15 resources.  All equal with utilization 1.
All nodes are off.
Node1 turns on.  Joins cluster.  10 resources start. 
Some time later, node2 turns on.  Joins cluster.  5 resources start.  Resources are distributed how?  10 on node1 and 5 on node2?  Will some resources migrate to node2?
And even later, node3 turns on.  Joins cluster.  No more resources start.  Resources are distributed how?  10 on node1 and 5 on node2 and 0 on node3?  Or will some resources migrate to node3?

Our clustering has been very successful to this point.  We are considering future options.

Mark K Vallevand   Mark.Vallevand at Unisys.com <mailto:Mark.Vallevand at Unisys.com> 
Never try and teach a pig to sing: it's a waste of time, and it annoys the pig.

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-----Original Message-----
From: linux-cluster-bounces at redhat.com [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Michael Schwartzkopff
Sent: Thursday, October 01, 2015 11:40 AM
To: linux clustering
Subject: Re: [Linux-cluster] Resource placement after node comes online.

Am Donnerstag, 1. Oktober 2015, 16:25:48 schrieb Vallevand, Mark K:
> In a multiple node cluster with resources distributed across the nodes, is
> there a way to automatically 'rebalance' resources when a node comes
> online?

pacemaker decides where to stop / start resources based on a score system 
every time the cluster receives an event. A node joing the cluster is 
definitely an event that triggers a recalculation of the scores that a resource 
would collect on every node.

Baed on constraints you can configure your cluster to re-distribute resources 
in a very granular way.

Dr. Michael Schwartzkopff
Guardinistr. 63
81375 München

Tel: (0162) 1650044
Fax: (089) 620 304 13

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