[Pacemaker] DRBD M/S Promotion

[Scott Piazza]

I have a two-node active/passive pacemaker cluster running with a single
DRBD resource set up as master-slave.  Today, we restarted both servers
in the cluster, and when they came back up, both started pacemaker and
corosync correctly, but the DRBD resource didn't promote.  I manually
promoted the DRBD resource and all of the child services were able to
start up without issue.  There were no error counts showing in
crm_mon.  

The only error I noted in the /var/log/messages log referenced not being
able to mount /dev/drbd0 because the device wasn't present.

CIB is available at http://pastebin.com/4b6Fi87w.

I'm trying to figure out what is wrong with my configuration.  Any
insights would be much appreciated.