[Pacemaker] Starting a cloned resource only on nodes running another resource

[Andrew Beekhof]

On Wed, Nov 18, 2009 at 10:50 PM, Ashley Winters
<Ashley.Winters at freedomvoice.com> wrote:
> Andrew Beekhof wrote,
>>
>> On Wed, Nov 18, 2009 at 12:11 AM, Ashley Winters
>> <Ashley.Winters at freedomvoice.com> wrote:
>> > I want to start a single instance of resource A on any node which is
>> > running one or more instances of resource B. And, I don't want to stop
>> > resource A until there are no more instances of resource B on that
>> > node. I'm using pacemaker 1.0.5 & openais 0.80.5.
>>
>> You might find the following link useful.
>>   http://clusterlabs.org/doc/en-US/Pacemaker/1.0/html/Pacemaker_Explained/s-resource-sets-collocation.html
>
> That was tantalizingly close to the solution I needed, but the colocation
> constraint over a resource_set won't distribute over my cloned resource.
>
> <constraints>
>  <rsc_colocation id="colo-route" score="INFINITY">
>    <resource_set id="set-route" sequential="true">
>      <resource_ref id="cl-route"/>
>    </resource_set>
>    <resource_set id="set-route-ip" sequential="false">
>      <resource_ref id="ip1"/>
>      <resource_ref id="ip2"/>
>    </resource_set>
>  </rsc_colocation>
> </constraints>
>
> Experimentally, that constraint only allows cl-route to run on a node with
> both resources running on it, rather than on any node where one of them
> is running. Setting up two different colocation constraints with one ip
> each doesn't change the behavior. In either case, both resources *have*
> to be running, and both on the same node, before the cl-route will be
> started.

Could you send me a testcase (cibadmin -Ql while the cluster is in the
bad state), you might have hit a bug.

>
> The documentation I read mentioned a possible configuration where "B would
> be allowed to remain active even if A or C (or both) were inactive" but
> apparently sequential="false" didn't trigger it.
>
> Is there a way to convince pacemaker to run the colocation test
> independently for each node & ip resource? Something like an 'or'?
>
> Thanks,
>
> - Ashley Winters
>
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