[Bug 1828617] Re: Hosts randomly 'losing' disks, breaking ceph-osd service enumeration

[Steve Langasek]

> LVM module is supposed to create PVs from devices using the links in /dev/disk/by-dname/
> folder that are created by udev.

Created by udev how?  disk/by-dname is not part of the hierarchy that is
populated by the standard udev rules, nor is this created by lvm2.  Is
there something in the ceph-osd packaging specifically which generates
these links - and, in turn, depends on them for assembling LVs?

Can you provide udev logs (journalctl --no-pager -lu systemd-
udevd.service; udevadm info -e) from the system following a boot when
this race is hit?

** Changed in: systemd (Ubuntu)
       Status: Confirmed => Incomplete

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Title:
  Hosts randomly 'losing' disks, breaking ceph-osd service enumeration

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  Ubuntu 18.04.2 Ceph deployment.

  Ceph OSD devices utilizing LVM volumes pointing to udev-based physical devices.
  LVM module is supposed to create PVs from devices using the links in /dev/disk/by-dname/ folder that are created by udev.
  However on reboot it happens (not always, rather like race condition) that Ceph services cannot start, and pvdisplay doesn't show any volumes created. The folder /dev/disk/by-dname/ however has all necessary device created by the end of boot process.

  The behaviour can be fixed manually by running "#/sbin/lvm pvscan
  --cache --activate ay /dev/nvme0n1" command for re-activating the LVM
  components and then the services can be started.

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