root on raid device doesn't get /dev/disk/by-id/md-{name,uuid} symlinks after boot

[Ryan Harper]

ubuntu@ubuntu:~$ lsb_release -rd
Description: Ubuntu Zesty Zapus (development branch)
Release: 17.04
ubuntu@ubuntu:~$ uname -a
Linux ubuntu 4.9.0-15-generic #16-Ubuntu SMP Fri Jan 20 15:28:49 UTC 2017 ppc64le ppc64le ppc64le GNU/Linux

ubuntu@ubuntu:~$ apt-cache policy systemd
systemd:
  Installed: 232-8
  Candidate: 232-8
  Version table:
 *** 232-8 500
        500 http://ports.ubuntu.com/ubuntu-ports zesty/main ppc64el Packages
        100 /var/lib/dpkg/status

3) root@ubuntu:~# ls -al /dev/disk/by-id/md-*
lrwxrwxrwx 1 root root 9 Feb 10 19:42 /dev/disk/by-id/md-name-ubuntu:foobar -> ../../md0
lrwxrwxrwx 1 root root 9 Feb 10 19:42 /dev/disk/by-id/md-uuid-bd97a135:166d5e7e:29e6b0eb:a3cad7c3 -> ../../md0

4)root@ubuntu:~# ls -al /dev/disk/by-id/md-* returns nothing

Note, I can re-trigger events on md0 and the links will appear.

udevadm test $(udevadm info -q path -n /dev/md0)

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: udev 232-8
ProcVersionSignature: User Name 4.9.0-15.16-generic 4.9.5
Uname: Linux 4.9.0-15-generic ppc64le
.var.log.platform: Error: [Errno 13] Permission denied: '/var/log/platform'
ApportVersion: 2.20.4-0ubuntu1
Architecture: ppc64el
CustomUdevRuleFiles: main_disk-part1.rules.rules third_disk.rules.rules md0.rules.rules second_disk-part1.rules.rules second_disk.rules.rules third_disk-part1.rules.rules main_disk-part2.rules.rules fourth_disk.rules.rules fourth_disk-part1.rules.rules main_disk.rules.rules
Date: Fri Feb 10 19:38:42 2017
Lsusb: Error: command ['lsusb'] failed with exit code 1:
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinux-4.9.0-15-generic root=UUID=a8f0a084-efb9-11e6-9e80-525400123456 ro console=hvc0
ProcLoadAvg: 0.32 0.17 0.06 1/146 6210
ProcLocks:
 1: POSIX ADVISORY WRITE 5006 00:12:22238 0 EOF
 2: POSIX ADVISORY WRITE 5015 00:12:22033 0 EOF
 3: FLOCK ADVISORY WRITE 5007 00:12:22011 0 EOF
 4: POSIX ADVISORY WRITE 4979 00:12:21491 0 EOF
 5: POSIX ADVISORY WRITE 2643 00:12:13926 0 EOF
ProcSwaps:
 Filename Type Size Used Priority
 /swap.img file 1157056 0 -1
ProcVersion: Linux version 4.9.0-15-generic (buildd@bos01-ppc64el-020) (gcc version 6.3.0 20161229 (User Name 6.3.0-2ubuntu1) ) #16-User Name SMP Fri Jan 20 15:28:49 UTC 2017
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
cpu_cores: Number of cores present = 1
cpu_coreson: Number of cores online = 1
cpu_smt: Error: command ['ppc64_cpu', '--smt'] failed with exit code 255: Machine is not SMT capable

[Dimitri John Ledkov (xnox)]

There are a lot of custom udev rules

CustomUdevRuleFiles: main_disk-part1.rules.rules third_disk.rules.rules md0.rules.rules second_disk-part1.rules.rules second_disk.rules.rules third_disk-part1.rules.rules main_disk-part2.rules.rules fourth_disk.rules.rules fourth_disk-part1.rules.rules main_disk.rules.rules

Can you attach them?

Are all of those included in the initramfs as well? (check with e.g. lsinitramfs)

The md-name and md-uuid symlinks are generated by the udev rules shipped by the mdadm package.

[Ryan Harper (raharper)]

> Are all of those included in the initramfs as well? (check with e.g. lsinitramfs)

No; but they don't need to be; it's purely helpful symlinks to provide a "name" for a device that's independent of the disk (/dev/disk/by-dname/database -> /dev/vdc).

drwxr-xr-x 2 root root 0 Mar 28 14:24 lib/udev/rules.d
-rw-r--r-- 1 root root 4250 Nov 14 01:05 lib/udev/rules.d/69-lvm-metad.rules
-rw-r--r-- 1 root root 2710 Dec 17 00:54 lib/udev/rules.d/71-seat.rules
-rw-r--r-- 1 root root 5832 Dec 17 00:54 lib/udev/rules.d/60-persistent-storage.rules
-rw-r--r-- 1 root root 961 Dec 17 00:54 lib/udev/rules.d/73-special-net-names.rules
-rw-r--r-- 1 root root 3310 Dec 17 00:54 lib/udev/rules.d/50-udev-default.rules
-rw-r--r-- 1 root root 1051 Jun 26 2015 lib/udev/rules.d/69-bcache.rules
-rw-r--r-- 1 root root 452 Dec 17 00:54 lib/udev/rules.d/75-net-description.rules
-rw-r--r-- 1 root root 2130 Mar 28 14:24 lib/udev/rules.d/63-md-raid-arrays.rules
-rw-r--r-- 1 root root 618 Dec 17 00:54 lib/udev/rules.d/80-drivers.rules
-rw-r--r-- 1 root root 210 Dec 17 00:54 lib/udev/rules.d/50-firmware.rules
-rw-r--r-- 1 root root 456 Dec 17 00:54 lib/udev/rules.d/61-persistent-storage-android.rules
-rw-r--r-- 1 root root 2446 Nov 14 01:05 lib/udev/rules.d/56-lvm.rules
-rw-r--r-- 1 root root 6919 Nov 14 01:05 lib/udev/rules.d/55-dm.rules
-rw-r--r-- 1 root root 1495 Nov 14 01:05 lib/udev/rules.d/60-persistent-storage-dm.rules
-rw-r--r-- 1 root root 692 Dec 17 00:54 lib/udev/rules.d/73-usb-net-by-mac.rules
-rw-r--r-- 1 root root 292 Dec 17 00:54 lib/udev/rules.d/80-net-setup-link.rules
-rw-r--r-- 1 root root 1366 Mar 28 14:24 lib/udev/rules.d/64-md-raid-assembly.rules

> The md-name and md-uuid symlinks are generated by the udev rules shipped by the mdadm package.

Correct; which is why it appears to be a bug in mdadm; that package provides the rules file.