[Bug 569900] Re: partman sometimes creates partitions such that there is ambiguity between whether the superblock is on the disk device or the partition device

[Ubuntu QA's Bug Bot]

** Tags added: testcase

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Title:
  partman sometimes creates partitions such that there is ambiguity
  between whether the superblock is on the disk device or the partition
  device

Status in “grub2” package in Ubuntu:
  Invalid
Status in “partman-base” package in Ubuntu:
  Fix Released
Status in “grub2” source package in Lucid:
  Invalid
Status in “partman-base” source package in Lucid:
  Fix Released
Status in “grub2” source package in Maverick:
  Invalid
Status in “partman-base” source package in Maverick:
  Fix Released

Bug description:
  Binary package hint: mdadm

  In a KVM, I can do this just fine:

   * Using 2 virtual disk images
   * Install Lucid Server amd64
   * Both disks partitioned to just one large Linux raid partition
   * RAID1 these two together, /dev/md0
   * Put / on an ext4 filesystem on /dev/md0
   * Install

  The above works.

  However, I have spent my entire weekend trying to get 10.04 on a RAID1
  of two 500GB SATA disks, without success.

  I partitioned them the same as above.  And conducted the install.

  When I boot into the new system, I get dropped to an initramfs shell.

  I can see that /dev/md0 exists, and is in the process of resyncing.

  I try to "mount /dev/md0 /root" and I get:
  mount: mounting /dev/md0 on /root/ failed: Invalid argument

  Also, see something else that's odd...  My /dev/md0 looks "correct",
  in that it's composed of /dev/sda1 and /dev/sdb1.  However, I also see
  a /dev/md0p1, which is composed of /dev/sda and /dev/sdb (the whole
  disks?).  Furthermore, if I go into /dev/disk/by-uuid, there is only
  one symlink there, pointing to /dev/md0p1.  And this UUID is what is
  in fact in grub as the root device.  That looks quite wrong.

  This looks pretty release-critical, to me, as it's affecting RAID
  installs of the server.

  TEST CASE: The above problem should arise when attempting a RAID
  install on any disk whose size is between 1048576*n+512 and
  1048576*n+65535 bytes, for integer values of n.  In order to reproduce
  this, the root filesystem should be created on a RAID array whose
  member devices extend all the way to the end of the disk (i.e. accept
  the default size for the partition in the installer).

  To validate this from -proposed (once available), please note that you
  will need to use a netboot installation image and boot with apt-
  setup/proposed=true on the kernel command line.

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