Public bug reported:
When pulling out a disk on my 12.04.2 RAID1 setup, which contains a LUKS
container inside an md device, my system won't boot. Plugging the second
disk back in worked, but I wanted to replace my disks, and if a disk is
broken you don't have that option...
Debugging the initramfs boot sequence seems to indicate that the crypto
handling is done before degraded array handing, rendering the
BOOTDEGRADED flag ineffective.
I've looked at other bugs (#1077650 #1003309 #728435 #106215) but I
think it's a different problem.
Situation
I've got a LVM-in-LUKS-in-RAID1 setup, with a separate, RAID'ed
bootpartition.
# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4]
[raid10]
md126 : active raid1 sda2[0] sdb2[2]
523968 blocks super 1.2 [2/2] [UU]
md127 : active raid1 sda1[0] sdb1[2]
976106048 blocks super 1.2 [2/2] [UU]
unused devices: <none>
md127 contains a LUKS container, called ugh2_lvm.
ugh2_lvm contains an LVM with a volume group called ugh2_vg.
ugh2_vg contains LV's called "root" (the root filesystem) and "swap".
# mount | grep /dev/m
/dev/mapper/ugh2_vg-root on / type ext4 (rw,relatime)
/dev/md126 on /boot type ext4 (rw)
# cat crypttab
ugh2_lvm UUID=69ade3d3-817d-42ee-991b-ebf86e9fe685 none luks
# grep 'DEGRADED=' /etc/initramfs-tools/conf.d/mdadm
BOOT_DEGRADED=true
Symptoms
Booting seems to hang with a message "evms_activate is not available".
I'm not using EVMS so the message is not really indicative of the
problem. Perhaps you get dropped to a shell after a lot of time (3
minutes? I saw a time-out of 180 seconds in the scripts somewhere) but
that took too long for me.
Diagnosis
Interrupting the boot process with break=premount let me take a look at
the situation. Turns out the degraded arrays assembled, but inactive;
the BOOT_DEGRADED handling activates the degraded arrays (scripts/local-
premount/mdadm). However, it does not get the chance to do so before the
scripts try to open the LUKS device with the configured UUID, since this
is done by scripts/local-top/cryptroot. "*-top" scripts are run before
"*-premount" scripts.
Workaround / solution
I made it work again by linking /usr/share/initramfs-tools/scripts
/local-premount/mdadm -> /etc/initramfs-tools/scripts/local-top/mdadm,
then rebuilding my initramfs (update-initramfs -u).
It seems to work well. Not sure if it's the best or even a clean
approach.
** Affects: initramfs-tools (Ubuntu)
Importance: Undecided
Status: New
** Tags: degraded initramfs-tools luks precise raid
** Attachment added: "Apport report for initramfs-tools on reporter's system."
https://bugs.launchpad.net/bugs/1196693/+attachment/3720969/+files/initramfs-tools.apport
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https://bugs.launchpad.net/bugs/1196693
Title:
Cannot boot degraded RAID1 array with LUKS partition
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