[Bug 803749] [NEW] grub-install fails during d-i installation when /boot/grub is located on md raid device

[Max Bowsher]

Public bug reported:

I have experienced a failure to install Ubuntu natty, using the d-i
(alternate, not ubiquity) installer.

The actual failure occurs when the installer executes grub-install.
Debugging a bit shows that the actual failing command is "grub-probe -t
fs /boot/grub". Debugging a bit more shows that /boot/grub is in my
situation, located on /dev/md0, and the failure involves grub-probe
attempting to execute /dev/md/0 (note: md/0, not md0) which does not
exist during the installer run.

A further point of interest found by looking into the grub code is that
grub only ends up looking for md/0 rather than md0 if the array is using
a version 1 md superblock - i.e. my problem is worked around by using a
version 0.90 md superblock.

But, there seems to be some other wrinkle involved that I have not yet
diagnosed, as the above problems were experienced on real hardware,
using a partman-auto-raid recipe, whilst attempting a kvm test install
without the preseed resulted in the md/0 symlink being created. More
info to come...

Other notes - the following bugs may be related to some degree:
bug 713874
bug 789226
bug 701351

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/803749

Title:
  grub-install fails during d-i installation when /boot/grub is located
  on md raid device

Status in “grub2” package in Ubuntu:
  New

Bug description:
  I have experienced a failure to install Ubuntu natty, using the d-i
  (alternate, not ubiquity) installer.

  The actual failure occurs when the installer executes grub-install.
  Debugging a bit shows that the actual failing command is "grub-probe
  -t fs /boot/grub". Debugging a bit more shows that /boot/grub is in my
  situation, located on /dev/md0, and the failure involves grub-probe
  attempting to execute /dev/md/0 (note: md/0, not md0) which does not
  exist during the installer run.

  A further point of interest found by looking into the grub code is
  that grub only ends up looking for md/0 rather than md0 if the array
  is using a version 1 md superblock - i.e. my problem is worked around
  by using a version 0.90 md superblock.

  But, there seems to be some other wrinkle involved that I have not yet
  diagnosed, as the above problems were experienced on real hardware,
  using a partman-auto-raid recipe, whilst attempting a kvm test install
  without the preseed resulted in the md/0 symlink being created. More
  info to come...

  Other notes - the following bugs may be related to some degree:
  bug 713874
  bug 789226
  bug 701351

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