Comment 14 for bug 1828617

Charm is cs:ceph-osd-284
Ceph version is 12.2.11-0ubuntu0.18.04.2

The udev rules are created by curtin during the maas install.

Here's an example udev rule:

cat bcache4.rules

# Written by curtin
SUBSYSTEM=="block", ACTION=="add|change", ENV{CACHED_UUID}=="7b0e872b-ac78-4c4e-af18-8ccdce5962f6", SYMLINK+="disk/by-dname/bcache4"

The problem here is that when the host boots, for some OSDs (random, changes each boot), there's no symlinks for block.db and block.wal in /var/lib/ceph/osd/ceph-${thing}. If I manually create those two symlinks (and make sure the perms are right for the links themselves), then the OSD starts.

Some of the OSDs do get those links though, and that's interesting because on these hosts, the ceph wal and db for all the OSDs are LVs on the same nvme device, in fact the same partition even. The ceph OSD block dev is an LV on a different device.