[Pacemaker] HA NFS Server requires NFS clone resource?

[Andrew Martin]

Hello,

Reading through the "Highly Available NFS storage with DRBD and Pacemaker" guide 
available here, http://www.linbit.com/en/downloads/tech-guides, I see that it
recommends that the lsb:nfs-kernel-server resource is configured as a clone:
clone cl_lsb_nfsserver p_lsb_nfsserver

I also found in this thread (http://oss.clusterlabs.org/pipermail/pacemaker/2011-July/010996.html)
that it was mentioned that the clone resource is there for a reason. Why
is this clone nfs-kernel-server necessary? Is it not sufficient to only start
this resource on the node actively mounting the DRBD resource?

Thanks,

Andrew