root@ceph-mon0:~# ceph-mon --mkfs -i 0 --keyring /var/lib/ceph/tmp/keyring.mon.0
ceph-mon: set fsid to e80afa94-a64c-486c-9e34-d55e85f26406
IO error: /var/lib/ceph/mon/mon.0/store.db/LOCK: No such file or directory
ceph-mon: error opening mon data directory at '/var/lib/ceph/mon/mon.0': (22) Invalid argument