root@pp-ceph-1:~# ceph osd tree

# id    weight  type name       up/down reweight
-1      5.46    root default
-2      2.73            host pp-ceph-1
0       0.91                    osd.0   up      1
1       0.91                    osd.1   up      1
2       0.91                    osd.2   up      1
-3      2.73            host pp-ceph-2
3       0.91                    osd.3   down    0
4       0.91                    osd.4   down    0
5       0.91                    osd.5   down    0

root@pp-ceph-1:~# /etc/init.d/ceph -a start osd.3
/etc/init.d/ceph: osd.3 not found (/etc/ceph/ceph.conf defines mon.pp-ceph-1 osd.0 osd.1 osd.2 mds.pp-ceph-1 , /var/lib/ceph defines mon.pp-ceph-1 osd.0 osd.1 osd.2 mds.pp-ceph-1)