[Pacemaker] Live migration with order constraints

[Andreas Kurz]

On 11/09/2011 10:46 PM, Dmitry Golubev wrote:
> Hi,
> 
> I am trying to make a live migration of virtual machines (custom resource
> agent). The idea is to suspend the virtual machine on one node, remount a
> filesystem (on top of DRBD) on another node and resume the virtual machine.

May I ask: Why? There is already the VirtualDomain RA which works fine,
including live migration.

> I have order constraints there to say that the virtual machine can only be
> run once the filesystem is mounted on the node. The problem is, however, that
> I can't live-migrate with such constraints:
> 
> notice: check_stack_element: Cannot migrate vcluster-vz1 due to dependency on
> drbd-r0-fs (order)
> 
> If I understand correctly, pacemaker can not migrate a resource if it depends
> on some other resource. But is there any way to force other resources to move
> together with the migrating resource?

Yes, migration only works without order-contraints the migrating service
depends on ... and no way to force it.

> 
> In the worst case scenario I will try to have an additional parameter to my
> resource agent to force move the dependent resources... but I am looking for
> the right way to solve this problem, not some ugly hack.
> 
> Any ideas?

Use existing, working and tested RAs.

Regards,
Andreas

-- 
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> 
> Thanks,
> Dmitry
> 
> 
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