[Linux-HA] Xen multiple resource instance prevention

[Dominik Klein]

>> I love the fact that when I force migrate a resource to the other node
>> it sets automatically up a -INFINITY to the other node doing exactly
>> what I want.
>>
>> I tried setting up the preferred node with INFINITY and the other with
>> -INFINITY but then the migration didn't work.
> 
> odd, it probably should.  can you include logs?

Not odd, imho. When migrating via a constraint that sets -inf for the 
current host, then both hosts are scored -inf so the rsc cannot run 
anywhere. At least thats my understanding of this case.

Regards
Dominik

ps. I do the same thing with Xen domU using a DRBD device. There, DRBD 
makes sure the domU does not run on more than one host at a time.