[Pacemaker] pacemaker resource constraints

[Andrew Beekhof]

On Tue, Mar 23, 2010 at 11:51 PM, Alan Jones <falancluster at gmail.com> wrote:
> BTW: The order matters in the colocation rule.  When I configure:
> colocation colo-master_worker -1: master worker
> Then "failback" is blocked by the stickiness.  In my opinion this is a bug,
> but others may have an explanation.

The order is significant....
   colocation colo-master_worker -1: master worker
is not the same as:
   colocation colo-master_worker -1: worker master

But there may be something else going on, so I'll certainly take a
look if you file a bug.
Be sure to include the full CIB when the cluster is in the state you
described (ie. preventing failback)

> This is the default version that installs on FC12 using the GUI software
> packages tools.
> Alan
>
> On Tue, Mar 23, 2010 at 3:47 PM, Alan Jones <falancluster at gmail.com> wrote:
>>
>> The following rules give me the behavior I was looking for:
>>
>> primitive master ocf:pacemaker:Dummy meta resource-stickiness="INFINITY"
>> is-managed="true"
>> location l-master_a master 1: fc12-a
>> location l-master_b master 1: fc12-b
>> primitive master ocf:pacemaker:Dummy
>> location l-worker_a worker 1: fc12-a
>> location l-worker_b worker 1: fc12-b
>> colocation colo-master_worker -1: worker master
>>
>> To recap, the goal is an active-active two node cluster were "master" is
>> sticky and "master" and "worker" with anti-colocate when possible for
>> performance.
>> Note that I had to add points for each resource on each node to overcome
>> the negative colocation value to allow them both to run on one node.
>> If there is a more elegant solution, let me know.
>> Alan
>>
>> On Tue, Mar 23, 2010 at 8:24 AM, Andrew Beekhof <andrew at beekhof.net>
>> wrote:
>>>
>>> On Mon, Mar 22, 2010 at 9:18 PM, Alan Jones <falancluster at gmail.com>
>>> wrote:
>>> > Well, I guess my configuration is not as common.
>>> > In my case, one of these resources, say resource A, suffers greater
>>> > disruption if it is moved.
>>> > So, after a failover I would prefer that resource B move, reversing the
>>> > node
>>> > placement.
>>> > Is this possible to express?
>>>
>>> Make A stickier than B.
>>>
>>> Please google for the following keywords:
>>>    site:clusterlabs.org resource-stickiness
>>>
>>> > Alan
>>> >
>>> > On Mon, Mar 22, 2010 at 11:10 AM, Dejan Muhamedagic
>>> > <dejanmm at fastmail.fm>
>>> > wrote:
>>> >>
>>> >> Hi,
>>> >>
>>> >> On Mon, Mar 22, 2010 at 09:29:50AM -0700, Alan Jones wrote:
>>> >> > Friends,
>>> >> > I have what should be a simple goal.  Two resources to run on two
>>> >> > nodes.
>>> >> > I'd like to configure them to run on separate nodes when available,
>>> >> > ie.
>>> >> > active-active,
>>> >> > and provide for them to run together on either node when one fails,
>>> >> > ie.
>>> >> > failover.
>>> >> > Up until this point I have assumed that this would be a base use
>>> >> > case
>>> >> > for
>>> >> > Pacemaker, however, it seems from the discussion on:
>>> >> > http://wiki.lustre.org/index.php/Using_Pacemaker_with_Lustre
>>> >> > ... that it is not (see below).  Any ideas?
>>> >>
>>> >> Why not just two location constraints (aka node preferences):
>>> >>
>>> >> location l1 rsc1 100: node1
>>> >> location l2 rsc2 100: node2
>>> >>
>>> >> Thanks,
>>> >>
>>> >> Dejan
>>> >>
>>> >> > Alan
>>> >> >
>>> >> > *Note:* Use care when setting up your point system. You can use the
>>> >> > point system if your cluster has at least three nodes or if the
>>> >> > resource
>>> >> > can acquire points from other constraints. However, in a system with
>>> >> > only two nodes and no way to acquire points, the constraint in the
>>> >> > example above will result in an inability to migrate a resource from
>>> >> > a
>>> >> > failed node.
>>> >> >
>>> >> > The example they refer to is similar to yours:
>>> >> >
>>> >> > # crm configure colocation colresOST1resOST2 -100: resOST1 resOST2
>>> >>
>>> >> > _______________________________________________
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>>> >>
>>> >>
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>>> >
>>> >
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>>
>
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