Hi everyone,
I'm working with a test configuration containing 128 resources using the
Stateful example resource agent supplied with Linux HA. I'm trying to
figure out how to get resource colocation constraints working efficiently.
I have 128 master/slave Stateful resources with a configuration for each
that looks like this:
<master id="ms_stateful_1">
<primitive id="stateful1" class="ocf" provider="pacemaker"
type="Stateful"/>
<instance_attributes id="params-stateful1">
<nvpair id="stateful1-clone-max" name="clone-max" value="2"/>
<nvpair id="stateful1-clone-node-max" name="clone-node-max"
value="1"/>
<nvpair id="stateful1-master-max" name="master-max" value="1"/>
<nvpair id="stateful1-master-node-max" name="master-node-max"
value="1"/>
<nvpair id="stateful1-resource-stickiness"
name="resource-stickiness" value="10"/>
</instance_attributes>
</master>
I then have a default score of 10000 assigned to each resource by using a
resource location constraint like this:
<rsc_location id="stateful1_default-score1" rsc="ms_stateful_1">
<rule id="stateful1_default-score2" score="10000">
<expression id="stateful1_default_expr" attribute="#uname"
operation="defined"/>
</rule>
</rsc_location>
I would then like to specify a resource colocation constraint that would
spread out the master and slave resources among cluster nodes as much as is
possible. I have figured out that this is possible to do by creating rules
like this with negative scores:
<rsc_colocation id="stateful1_2" rsc="ms_stateful_1"
with-rsc="ms_stateful_2" score="-7"/>
<rsc_colocation id="stateful1_2_ms" rsc="ms_stateful_1"
with-rsc="ms_stateful_2" with-rsc-role="Master" score="-7"/>
This causes resources to prefer to be placed on nodes where the fewest
number of resources are running to spread them out to the largest extent
possible.
These resource colocation constraints work well for a small number of
resources, but it requires defining colocation constraints for all
permutations of resources. For 5 resources this is manageble, I define
colocation constraints between resources like this:
1->2
1->3
1->4
1->5
2->3
2->4
2->5
etc.
but for large numbers of resources (like 128) this simply is not scalable.
Is there a more efficient way to define the colocation constraints instead
of requiring an explicit constraint for each combination of resources?
Thanks in advance for your help!
Regards,
Eric Blau
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