In my original bug report, I used 8.04.1 that had been live upgraded to
8.04.2. Recently, I tried installing the same setup (RAID1 + encryption
+ LVM) on another computer, this time directly from Ubuntu 8.04.2
Alternate installation disk. Installation went fine, but in the very
first boot after installation the computer did not start. I got these
messages when I rebooted without "quiet splash" boot options:

md: invalid raid superblock magic on sda
raid array is not clean -- starting background reconstruction
check root= bootarg cat /proc/cmdline or missing modules, devices: cat 
/proc/modules ls 
/dev ALERT! /dev/mapper/lvm_group-lvm_root does not exist

I got dropped to busybox. "ls /dev/mapper" did not reveal any md
devices, so the error seemed correct. Then I figured to test "cat
/proc/mdstat". Everything was fine there, both disks up, resync
ongoing... First I could not figure out what was going on as the same
setup method had previously worked. Then I realized that I was now using
8.04.2 installation disk, which includes some changes for degraded RAID
boot procedure. I had already filed this bug, related to degraded RAID
and encryption. And, what do you know, after typing the same fix in
Busybox "cryptsetup luksOpen /dev/md1 md1_crypt" everything was going to
be ok again: with "ls /dev/mapper" I could see my devices. I waited
until RAID sync was over (cat /proc/mdstat shows the progress) and then
booted with CTRL+D. It worked. I rebooted, and this time LUKS password
was queried and system booted correctly.

So, what happened is very much related to this same bug: when you have
LUKS encryption on top of RAID 1 array, and the array gets degraded
either because of a disk is missing or, as in this case, needs to be
resynced, the system won't start. Now it seems even more fatal, as the
system fails to boot the very first time after installation, even if
both disks are present and working. And once again, error messaged do
not give hints to correct direction.

In this case, the problem could be handled at least partially by
printing a message that tells that RAID resync is going on, and you can
check its progress with this command, and when it is finished you can
restart the computer and then it will boot normally. Currently, the user
gets confused and probably thinks that the installation did not work at
all, although there's nothing wrong with it.

-- 
System startup fails with degraded RAID + encryption
https://bugs.launchpad.net/bugs/324997
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