[Pacemaker] Live migration with order constraints

[Dmitry Golubev]

> > > Actually, it's called ManageVE. Well, I wonder what else an RA
> > > could do other than manage :->
> > 
> > ah, yes .. ManageVE ... thx 
> 
> What I meant to say is that it's really hard to recall such a
> name.

With all due respect, ManageVE does not have live migration. It just manages
start/stop for a single virtual machine. What I need is to live-migrate a group
of virtual machines which reside on one filesystem all together to a different
node. Given that there might be more than one such group. Yes, it can be done
having a resource for each virtual machine - i wouldn't object to that at all,
but they must have live migration together with their underlying filesystem. I
can't have cluster filesystem there, which could be mounted on both nodes and
deliver the possibility to live-migrate everything without a glich or remounting,
but unfortunately OpenVZ supports quotas only on ext2/3/4... so no OCFS or
similar things for me :(

My resource agent correctly does that thing with OpenVZ restart on the second
node, but no live migration for now. Live migration (no matter, whether it is
OpenVZ or KVM) depends on filesystem being either present on both nodes
simultaneously (impossible with ext2/3/4) or unmounted/remounted (which requires
order and location constraints). If there is no clean solution, is it really
impossible to have one resource agent moving another resource (by issuing a
commandline instruction to the cluster resource manager)?

Thanks,
Dmitry