[Bug 290885] Re: SRU: Backport of Boot Degraded RAID functionality from Intrepid to Hardy

Dustin Kirkland dustin.kirkland at gmail.com
Tue Nov 4 20:09:11 UTC 2008


Stable Release Update requested for:
 * grub-installer
 * grub
 * mdadm
 * initramfs-tools

Per:
 * https://wiki.ubuntu.com/StableReleaseUpdates

 1) This set of bugs affects any Ubuntu 8.04 LTS user with / or /boot on
a RAID1 device.  RAID is intended to provide both redundancy of the data
on those filesystems, as well as failover reliability.  8.04 does not
currently handle the failover case very well, as a system with a
degraded RAID will not boot, leaving the system in the initramfs.  This
is a serious issue, and has yielded a very noisy contingent of Ubuntu
users asking for this fix on their LTS servers.  The remedy to this
problem is spread across some 4 separate packages and involves modified
code in both the installer and runtime OS.  The installer code (new
grub-installer udeb) would need to be included in the 8.04.2 install
media.

 2)   The code changes were surgically backported from Intrepid, where they have been tested extensively over the last 5 months.  A full design specification is available at:
 * https://wiki.ubuntu.com/BootDegradedRaid
Spefically the changes involve:
 * grub-installer - in the installer, iterate over each disk in an md device providing /boot, and write grub to each
 * grub - in a running system, enhance grub-install to operate properly on a /dev/md device, or each disk independently
 * mdadm - add failure hooks to the initramfs to handle a missing disk, prompting the user if they want to boot the degraded RAID, or obeying configured options; configure those options via debconf; add such debconf handling to the installer
 * initramfs-tools - add framework bits for handling mountroot failures and attempt recovery steps

 3) I have attached a gzipped tarball of all 4 patches.

 4) TEST CASE: Testing this is a rather long, arduous process.  I have
documented those processes in detail at
https://wiki.ubuntu.com/BootDegradedRaid.

 5) In terms of analyzing regression potential, I would probably need to
enlist the assistance of someone on the platform/foundations team.  I
think the most dangerous of changes are the ones in initramfs-tools, in
terms of affecting others.  I looked for reasonable callers that might
be affected, and I didn't find any, immediately.

These packages are currently available for testing in my PPA.  I have
functionally verified that they do the right thing on my Hardy vm's.  I
believe that they're ready for review by Colin, Evan, Luke, and/or Kees,
and then upload to hardy-proposed.

:-Dustin

** Attachment added: "SRU-290983-patches.tar.gz"
   http://launchpadlibrarian.net/19348268/SRU-290983-patches.tar.gz

-- 
SRU: Backport of Boot Degraded RAID functionality from Intrepid to Hardy
https://bugs.launchpad.net/bugs/290885
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