[Pacemaker] resource dependency

[Alexandre Biancalana]

On Fri, Nov 20, 2009 at 2:53 PM, Matthew Palmer <mpalmer at hezmatt.org> wrote:
> On Fri, Nov 20, 2009 at 02:42:29PM -0200, Alexandre Biancalana wrote:
>>  I'm building a 4 node cluster where 2 nodes will export drbd devices
>> via ietd iscsi target (storage nodes) and other 2 nodes will run xen
>> vm (app nodes) stored in lvm partition accessed via open-iscsi
>> initiator, using multipath to failover.
>>
>>  Configuring the cluster resources order I came up with a situation
>> that I don't find a solution. The xen vm resources depends of iscsi
>> initiator resource to run, I have two iscsi initiator resources, one
>> for each storage node, how can I make the vm resources dependent on
>> any iscsi initiator resources ?
>
> Personally, I think you've got the wrong design.  I'd prefer to loosely
> couple the storage and VM clusters, with the storage cluster exporting iSCSI
> initiators which the VM cluster then attaches to the VMs as required.  Put
> the error handling for the case where the iSCSI initiator isn't available
> for a VM into the resource agent for the VM.  To me, this seems like a more
> robust solution.  Tying everything up together feels like you're asking for
> trouble whenever any failover happens -- everything gets recalculated and the
> cluster spends the next several minutes jiggling resources around before
> everything settles back down again.

Hi Matt, thank you for the reply.

Ok. But if I go with your suggestion I end with the same question.

Having the 2 node storage cluster exporting the block device via
iSCSI, how can I make the VM resource at the VM cluster depend on
*any* iSCSI target exported ? The standard order configuration just
allow dependency on *one* resource.

The only way I see is configure a ip resource on storage cluster and
use this as portal on iSCSI initiator resource of VM cluster. I don't
want to do this way because I think use multipath, for a quicked
failover.

Alexandre