Today a disk did not come up anymore in the morning and I just noticed that the
bug is not fixed yet in mdadm-3.2.5-5ubuntu4.1.
In fact, it got worse "bootdegraded=yes" is now default (ubuntu 14.04) and
cannot be disabled anymore and so the system stays in an endless loop of
"mdadm: CREATE group disk not found" messages. The only chance to survice the
system was to boot a rescue system. As I didn't have a spare disk I had to get
the system to boot in degraded mode.
Below some diagnostics. Please note, I'm not familiar at all how the
Ubuntu initramfs scripts are assembled from their pieces.
Diagnostic 1) In /usr/share/initramfs-tools/scripts/mdadm-functions
I disabled (commented out) the incremental if-branch
( mdadm --incremental --run --scan; then), instead only the assemble mdadm
command run. After re-creating the initramfs and rebooting the "mdadm: CREATE
group disk not found" message was only shown *once*, it then complained that
it didn't find root partition and dropped to the busybox shell. MUCH BETTER!
Investigating on the shell I noticed that md devices had been assembled in
degraded mode. Also, running "mdadm --assemble --scan --run" and it brought up
the same disk group message. So seems to be a bug in mdadm to show this message
and to return an error code.
After running "vgchange -ay" I could leave the shell and continue to boot
Diagnostic 2) I now changed several things as we needed this system to
boot up automatically
2.1) I mad mountroot_fail to *always* execute 'vgchange -ay'
mountroot_fail()
{
mount_root_res=1
message "Incrementally starting RAID arrays..."
if mdadm --incremental --run --scan; then
message "Incrementally started RAID arrays."
mount_root_res=0
else
if mdadm --assemble --scan --run; then
message "Assembled and started RAID arrays."
mount_root_res=0
else
message "Could not start RAID arrays in degraded mode."
fi
fi
# note, if someone does that, she probably should change it to vgchange
-ay || true
vgchange -ay
return mount_root_res
}
2.2) /usr/share/initramfs-tools/scripts/init-premount/mdadm
case mountroot_fail now exits with 0, not with the exist code of
mountroot_fail
case $1 in
# get pre-requisites
prereqs)
prereqs
exit 0
;;
mountfail)
mountroot_fail
exit 0
;;
esac
. /scripts/functions
I think that is all I changed and the system now boots up in degraded mode like
a charm.
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https://bugs.launchpad.net/bugs/1077650
Title:
booting from raid in degraded mode ends in endless loop
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