[Bug 1019389] Re: Grub 2 hangs on boot after installing on RAID1 device (/dev/md0), reports no problems during install

[Iordan Iordanov]

In case it is relevant, here is a print out of the partition table, even
though (as mention previously), Grub 2 does install successfully when
the raw devices are specified (/dev/sda, /dev/sdb):

# parted /dev/md0 print

Model: Linux Software RAID Array (md)
Disk /dev/md0: 500GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start   End     Size    File system     Name   Flags
 1      17.4kB  8389kB  8372kB                  grub   bios_grub
 2      8389kB  21.0GB  21.0GB  ext4            root
 3      21.0GB  23.1GB  2097MB  linux-swap(v1)  swap
 4      23.1GB  33.6GB  10.5GB  ext4            var
 5      33.6GB  54.5GB  21.0GB  ext4            tmp
 6      54.5GB  75.5GB  21.0GB  ext4            local
 7      75.5GB  500GB   425GB   ext4            data

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https://bugs.launchpad.net/bugs/1019389

Title:
  Grub 2 hangs on boot after installing on RAID1 device (/dev/md0),
  reports no problems during install

Status in “grub2” package in Ubuntu:
  New

Bug description:
  This is 100% reproducible with metadata 0.9 and 1.0. We are installing
  a system with FAI (Fully Automatic Installation), and creating a full
  disk RAID1 array with two devices (/dev/sda and /dev/sdb). This
  results in a device /dev/md0 which we then label with a GPT label, and
  partition with parted, which gives us devices of the form /dev/md0p1,
  /dev/md0p2, etc.

  Since we are creating the RAID array with metadata 0.9 or 1.0, the
  metadata ends up at the end of the array, and so the BIOS should have
  no trouble reading from each disk individually to load the boot-
  loader, etc. What's more, grub2 supports GPT, and ordinarily has no
  trouble booting from a GPT labeled disk.

  At the end of the FAI installation, we install grub2 like this:

  grub-install /dev/md0

  which results in the usual "no errors reported" message that Grub2
  prints out. What we expect at this point is for md to automatically
  sync the grub2 changes to both /dev/sda and /dev/sdb, and for the BIOS
  to be able to boot from either device.

  What happens instead is that when the BIOS attempts to boot from
  either device, it hangs with a cursor blinking at the top-left corner
  of the screen *indefinitely*. So, it seems like although Grub 2 thinks
  the installation went fine, it is not actually OK.

  The interesting thing is that when we install Grub 2 to /dev/sda and
  /dev/sdb individually, rather than /dev/md0, everything works as
  intended. I've seen references on the web indicating that installing
  to the raw devices is the right thing to do, but I could not find any
  official documentation supporting the claims.

  If grub is supposed to be installed to /dev/sda and /dev/sdb, then the
  bug is that it doesn't complain when an attempt is made to install it
  to /dev/md0.

  If it should work even when installed to /dev/md0 (with metadata 0.9
  and 1.0), then the bug is that it doesn't actually install properly.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: grub2 1.99-21ubuntu3.1
  ProcVersionSignature: Ubuntu 3.2.0-25.40-generic 3.2.18
  Uname: Linux 3.2.0-25-generic i686
  ApportVersion: 2.0.1-0ubuntu8
  Architecture: i386
  Date: Fri Jun 29 15:21:36 2012
  ProcEnviron:
   TERM=xterm
   SHELL=/bin/bash
  SourcePackage: grub2
  UpgradeStatus: No upgrade log present (probably fresh install)

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