roles:
- [mon.a, mon.c, mgr.x, osd.0, osd.1, osd.2, osd.3]
- [mon.b, mgr.y, osd.4, osd.5, osd.6, osd.7]
- [client.0]
openstack:
- volumes: # attached to each instance
    count: 4
    size: 10 # GB
overrides:
  ceph:
    conf:
      osd:
        osd shutdown pgref assert: true