Comment 79 for bug 75681

my setup (taken from a booted system):

siretart-@hades:~
>> cat /proc/mdstat
Personalities : [raid0] [raid1]
md1 : active raid1 sda5[0] sdb5[1]
      1951744 blocks [2/2] [UU]

md0 : active raid1 sda2[0] sdb2[1]
      489856 blocks [2/2] [UU]

md3 : active raid0 sda7[0] sdb7[1]
      395632512 blocks 64k chunks

md2 : active raid1 sda6[0] sdb6[1]
      97659008 blocks [2/2] [UU]

unused devices: <none>

siretart-@hades:~
>> sudo lvs
  LV VG Attr LSize Origin Snap% Move Log Copy%
  backup hades_mirror -wi-ao 42,00G
  home hades_mirror -wi-ao 25,00G
  ubunturoot hades_mirror -wi-ao 25,00G
  chroot_dapper hades_stripe -wi-a- 5,00G
  chroot_dapper32 hades_stripe -wi-a- 5,00G
  chroot_edgy hades_stripe -wi-a- 5,00G
  chroot_edgy32 hades_stripe -wi-a- 5,00G
  chroot_feisty hades_stripe -wi-a- 5,00G
  chroot_feisty32 hades_stripe -wi-a- 5,00G
  chroot_sarge32 hades_stripe -wi-a- 3,00G
  chroot_sid hades_stripe -wi-a- 5,00G
  chroot_sid32 hades_stripe owi-a- 5,00G
  dapper32-snap hades_stripe -wi-a- 2,00G
  mirror hades_stripe -wi-ao 89,00G
  scratch hades_stripe -wi-ao 105,00G
  sid-xine-snap hades_stripe swi-a- 3,00G chroot_sid32 26,43
  ubunturoot hades_stripe -wi-ao 25,00G
siretart-@hades:~
>> sudo pvs
  PV VG Fmt Attr PSize PFree
  /dev/md2 hades_mirror lvm2 a- 93,13G 1,13G
  /dev/md3 hades_stripe lvm2 a- 377,30G 10,30G
siretart-@hades:~
>> sudo vgs
  VG #PV #LV #SN Attr VSize VFree
  hades_mirror 1 3 0 wz--n- 93,13G 1,13G
  hades_stripe 1 14 1 wz--n- 377,30G 10,30G

The (primary) root volume is /dev/hades_stripe/ubunturoot.

I wasn't able to reproduce the problem with the instructions you
gave. However, I modified
/usr/share/initramfs-tools/scripts/init-premount/udev to look like this:

--- /usr/share/initramfs-tools/scripts/init-premount/udev 2007-03-29 20:44:30.000000000 +0200
+++ /usr/share/initramfs-tools/scripts/init-premount/udev~ 2007-03-29 20:30:21.000000000 +0200
@@ -20,9 +20,10 @@
 # It's all over netlink now
 echo "" > /proc/sys/kernel/hotplug

+sleep 3
+
 # Start the udev daemon to process events
-#/sbin/udevd --daemon
-/sbin/udevd --verbose --suppress-syslog >> /tmp/udev-output 2>&1 &
+/sbin/udevd --daemon

 # Iterate sysfs and fire off everything; if we include a rule for it then
 # it'll get handled; otherwise it'll get handled later when we do this again

This way (okay, after two boots), I was able to reproduce the
problem. Here is the output of /proc/partitions:

 major minor
#blocks name

   8 0 312571224 sda
   8 1 14651248 sda1
   8 2 489982 sda2
   8 3 1 sda3
   8 5 1951866 sda5
   8 6 97659103 sda6
   8 7 197816346 sda7
   8 16 312571224 sdb
   8 17 14651248 sdb1
   8 18 489982 sdb2
   8 19 1 sdb3
   8 21 1951866 sdb5
   8 22 97659103 sdb6
   8 23 197816346 sdb7

Here the contents of /proc/mdstat:

Personalities : [raid0] [raid1]
md0 : inactive sdb2[1](S)
      489856 blocks

unused devices: <none>

mdstat -Q / mdstat -D don't work:
/dev/md0: is an md device which is not active
mdadm: md device /dev/md0 does not appear to be active.

In order to get the root device, I just need to (re)issue
'udevtrigger'. Then I can mount the root filesystem, copy the
debug output files.

Please note that the file udev-output contains the debug output
for the 2nd run of udevtrigger as well.