roles:
-- [mon.a, mgr.x, osd.0, mds.a, mds.b, client.1, client.2, client.3]
-- [client.0, osd.1, osd.2]
+- [mon.a, mgr.x, osd.0, osd.1, osd.2, osd.3, mds.a, mds.b, client.1, client.2, client.3]
+- [client.0, osd.4, osd.5, osd.6, osd.7]
openstack:
- volumes: # attached to each instance
count: 2