[Pacemaker] Master-Slave role stickiness

[Andrei Borzenkov]

On Wed, Jan 21, 2015 at 11:06 PM, brook davis <brook.davis at nimboxx.com> wrote:
> Hi,
>
> I've got a master-slave resource and I'd like to achieve the following
> behavior with it:
>
> * Only ever run (as master or slave) on 2 specific nodes (out of N possible
> nodes).  These nodes are predetermined and are specified at resource
> creation time.
> * Prefer one specific node (of the 2 selected for running the resource) for
> starting in the Master role.
> * Upon failover event, promote the secondary node to master.
> * Do not re-promote the failed node back to master, should it come back
> online.
>
> The last requirement is the one I'm currently struggling with.  I can force
> the resource to run on only the 2 nodes I want (out of 3 possible nodes),
> but I can't get it to "stick" on the secondary node as master after a
> failover and recovery.   That is, when I take the original master offline,
> the resource promotes correctly on the secondary, but if I bring the origin
> node back online, the resource is demoted on the secondary and promotes back
> to master on the origin.   I'd like to avoid that last bit.
>

It sounds like default-resource-stickiness does not kick in; and with
default resource-stickiness=1 it is expected (10 > 6).  Documentation
says default-recource-stickiness is deprecated so may be it is ignored
in your version altogether? What "ptest -L -s" shows?

> Here's the relevant bits of my CRM configuration:
>
> primitive NIMHA-01 ocf:heartbeat:nimha \
>     op start interval="0" timeout="60s" \
>     op monitor interval="30s" role="Master" \
>     op stop interval="0" timeout="60s" \
>     op monitor interval="45s" role="Slave" \
> ms NIMMS-01 NIMHA-01 \
>     meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1"
> notify="true" target-role="Started" is-managed="true"
> location prefer-elmy-inf NIMMS-01 5: elmyra
> location prefer-elmyra-ms NIMMS-01 \
>     rule $id="prefer-elmyra-rule" $role="Master" 10: #uname eq elmyra
> location prefer-pres-inf NIMMS-01 5: president
> location prefer-president-ms NIMMS-01 \
>     rule $id="prefer-president-rule" $role="Master" 5: #uname eq president
> property $id="cib-bootstrap-options" \
>     dc-version="1.1.10-42f2063" \
>     cluster-infrastructure="corosync" \
>     stonith-enabled="false" \
>     no-quorum-policy="ignore" \
>     last-lrm-refresh="1421798334" \
>     default-resource-stickiness="200" \
>     symmetric-cluster="false"
>
>
> I've set symmetric-cluster="false" to achieve an "opt-in" behavior, per the
> corosync docs.  From my understanding, these location constraints should
> direct the resource to be able to run on the two nodes, preferring 'elmyra'
> initially as Master.  My question then becomes, is there a way to apply the
> stickiness to the Master role ??   I've tried adding explicit stickiness
> settings (high numbers and INF) to the default-resource-stickiness, the
> actual "ms" resource, and the primitive, all to no avail.
>
> Anyone have any ideas on how to achieve stickiness on the master role in
> such a configuration ?
>
> Thanks for any and all help in advance,
>
> brook
>
> ps.  please ignore/forgive the no-quorum-policy and stonith-enabled settings
> in my configuration...  I know it's bad and not best practice.  I don't
> think it should affect the answer to the above question, though, based on my
> understanding of the system.
>
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