[Pacemaker] problem with colocating and ordering sets of resources

[Ronney Meier - Rorotec Informatik GmbH]

Hi all

I have a 2 node setup with lvm on top oft wo drbd devices and two xen virtual machines running.
The pacemaker version used is 1.0.11 .
All of the resources should always be running on the same node. 
This usually works, but last week after a crash it happened, that pacemaker made one of the drbd devices master on one node, and the other drbd device on the other node. So it couldn't bring up the lvm anymore and therefore also none of the other resources were able to run.
My colocation and order constraints look like that here:

colocation xen_on_drbd inf: ( xen-windows_server_sb xen-windows_server_standard ) fs-xendata lv-drbd_data ( ms-drbd_r0:Master ms-drbd_r1:Master )

order ord-xen_after_drbd inf: ( ms-drbd_r0:promote ms-drbd_r1:promote ) lv-drbd_data:start fs-xendata:start ( xen-windows_server_sb:start xen-windows_server_standard:start )

So that it should first promote the two drbd devices, then den bringing up the lvm (=lv-drbd_data), then mounting the filesystem with the xen images (=fs_xendata) and then starting up the virtual machines. 
Resources in the colocation constraint inside of parenthesis should be independent from each other.

If I didn't completely missunderstood how the colocation of sets works, it should be impossible, that pacemaker promotes the two drbd devices on different nodes. 
Or did I make an error with these constraints?

Thanks for any help in advance :-)

ronney