Upon startup, it will identify the logical volume using LVM tags, finding a matching ID and later ensuring it is the right one with the OSD uuid.
After identifying the correct volume it will then proceed to mount it by using the OSD destination conventions, that is:
/var/lib/ceph/osd/<cluster name>-<osd id>
For our example OSD with an id of
0, that means the identified device will
be mounted at:
Once that process is complete, a call will be made to start the OSD:
systemctl start ceph-osd@0
The systemd portion of this process is handled by the
trigger sub-command, which is only in charge of parsing metadata coming from
systemd and startup, and then dispatching to
ceph-volume lvm activate which
would proceed with activation.