Hello.

I'm trying to setup an highly available OpenVZ cluster. As OpenVZ only
supports disk quota on ext3/4 local filesystems  (nfs and gfs/ocfs2
don't work),
I have setup two iscsi volumes on an highly available storage where
VMs will be stored.
I would like to use three servers, two active and one spare, for this
cluster. That's because OpenVZ expects all the VMs to be under /vz or
/var/lib/vz directory. This leads to the constraint that each server
can have only on iscsi volume attached and mounted on /vz.
Also, as the ext3 fs is not a cluster filesystem, each iscsi volume
has to be mounted on a single server at time.

So I need to map two iscsi volumes to three servers. I have created a
pacemaker configuration with two groups, group-iscsi1 and
group-iscsi2, that take care of connecting the iscsi devices and
mounting the filesystems on /vz. A negative colocation directive
forbids the two groups from being active on the same cluster node at
the same time.

So far things are working. The problem is with the resource that
controls OpenVZ. It is a lsb:vz primitive that needs to be a clone (I
can't make it into separate lsb-vz1 or lsb-vz2 primitives as the
cluster sees both active on every node because they refer to the same
/etc/init.d/vz script).
After creating the clone clone-vz, I defined the location constraints
as location vz-on-iscsi inf: group-iscsi1 clone-vz and did the same
for group-iscsi2.
The clone resource needs to be started after filesystems are mounted,
so I need two order constraints like order vz-after-fs1 inf:
group-iscsi1:start clone-vz:start and order vz-after-fs2 inf:
group-iscsi2:start clone-vz:start
This works perfectly when both iscsi volumes are up. But if one of
them is stopped, clone-vz is not starting. I guess this is because the
two order constraints create dependencies for clone-vz on both the
iscsi groups so that the clone is started only when group-iscsi1 AND
group-iscsi2 have started.

Is there a way I can tell pacemaker to start clone-vz on a node if
that node has resource group-iscsi1 OR group-iscsi2?

The complete pacemaker configuration is here:
http://nopaste.info/8c2ba79159.html

Thanks,
Alessandro
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