Ceph

allow a special client type of 'all' to map to all clients. e.g.

roles:
 - [mon.a, mds.a, osd.0, client.2]
 - [mon.b, mds.a-s, osd.1, client.1]
 - [mon.c, client.0]
 tasks:
 - ceph:
 - rbd:
     all:

would map an rbd client on clients 0, 1, and 2.

Then fix up all the suite tasks that reference rbd to use 'all' (along with the workunits) so that they will magically map to multiple clients (if they exist).