[Pacemaker] Problem with Xen live migration

[Jean-Francois Malouin]

Back again to setup an active/passive cluster for Xen with live migration
but so far, no go. Xen DomU is shutdown and restarted when I move the
Xen resource.

I'm using Debian Squeeze, pacemaker 1.0.9.1, corosync 1.2.1-4 with Xen 4.0.1-1
and kernel 2.6.32-30. DRBD is at 8.3.8.

A logical volume 'xen_vg' is sitting on top of a drbd block device and an OCFS2
filesystem is created on the LV to hold the disk image for the Xen guest:

[ drbd resDRBDr1 ] -> [ LVM resLVM ] -> [ OCFS2 resOCFS2 ] 

The cluster logic is (timeouts, etc removed) something along those
lines:

primitive resDRBDr1 ocf:linbit:drbd params drbd_resource="r1" ...
primitive resLVM ocf:heartbeat:LVM params volgrpname="xen_vg" ...
primitive resOCFS2 ocf:heartbeat:Filesystem fstype="ocfs2" ...
primitive resXen1 ocf:heartbeat:Xen \
        params xmfile="/etc/xen/xen1cfg" name="xen1" \
        meta allow-migrate="true"
group groLVM-OCFS resLVM resOCFS2 
ms msDRBDr1 resDRBDr1 \
        meta notify="true" master-max="2" interleave="true"
colocation colLVM-OCFS-on-DRBDr1Master inf: groLVM-OCFS msDRBDr1:Master
colocation colXen-with-OcfsXen inf: resXen1 groLVM-OCFS
order ordDRBDr1-before-LVM inf: msDRBDr1:promote groLVM-OCFS:start
order ordLVM-OCFS-before-Xen inf: groLVM-OCFS:start resXen1:start

DRBD is configured with 'allow-to-primary'.

When I try to live migrate 'crm resource move' the Xen guest I get:

pengine: [11978]: notice: check_stack_element: Cannot migrate resXen1
due to dependency on group groLVM-OCFS (coloc)

and the guest is shutdown and restarted on the other node.

What am I missing? Something obvious or the cluster logic as it is
cannot permit live Xen migration? 

I have verified that Xen live migration works as (without pacemaker in
the picture) on the now passive node I can manually promote the drbd
block device, vgscan to scan for the logical volume, 'lvchange -ay' to
make it available, mount the OCFS2 filesystem, 'xm migrate --live' on
the active node, and the DomU is available on the other node.

Any help or examples very much appreciated!
jf