[root@iscsi-1 ~]# pcs resource delete --force DRBD-r0
Error: Resource does not exist.

[root@iscsi-1 ~]# pcs resource cleanup DRBD-r0
Resource: DRBD-r0 successfully cleaned up

[root@iscsi-1 ~]# pcs status
Cluster name: san-1
Last updated: Fri Oct 31 14:56:05 2014
Last change: Fri Oct 31 14:55:58 2014
Stack: cman
Current DC: iscsi-2 - partition with quorum
Version: 1.1.11-97629de
2 Nodes configured
2 Resources configured

Online: [ iscsi-1 iscsi-2 ]

Full list of resources:

 Dummy	(ocf::pacemaker:Dummy):	Started iscsi-1
 ClusterIP	(ocf::heartbeat:IPaddr2):	Started iscsi-2