To locate the host on which a given OSD lives, the ceph osd find command is invaluable.

 # ceph osd find 66 { "osd": 66, "ip": "10.8.45.17:6836/130331", "crush_location": { "host": "data003", "rack": "r1", "root": "default" } }

This is especially useful when monitoring detects that an OSD is down; the first step is typically to locate the host that houses it so that one may check it out, for example, by inspecting Ceph OSD and syslog files. In older Ceph releases, this command omitted the last newline, which was a bit awkward. As of the Ceph Jewel release this has been fixed.