[Bug 624219] Re: Boot partition missing: "Alert! dev/disk/by-uuid ... does not exist" and my preliminary solution

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: mdadm (Ubuntu)
       Status: New => Confirmed

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Title:
  Boot partition missing: "Alert! dev/disk/by-uuid ... does not exist"
  and my preliminary solution

Status in “mdadm” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: mdadm

  After a new installation of ubuntu 10.4 on an elder Computer (P III,
  900 MHz), on which I had installed elder versions of ubuntu before,
  when booting sometimes the quoted line above was shown, sometimes the
  system booted properly. The reasons according to the forums are 1) a
  problem of grub2 to handle UUIDs beyond certain conditions and 2)
  possible disturbing rests of data from grub legacy after an update to
  grub2. Research on the forums gave me two helpful hints. The first one
  is to reconfigure the grub2 when grub legacy was installed before and
  the upgrade was not performed by a specially designed program
  "upgrade-from-grub-legacy". The second one is to uncomment the line in
  the grub default file telling grub not to refer to the UUIDs and to
  run "update-grub2" afterwards. How to proceed:

  Open a terminal. sudo fdisk -l shows the linux partition ID by label
  such as /dev/sdaX (where X is the respective partition number).

  Run ubuntu from a live CD of your current version, "try" (do not
  install). The following steps will mount the relevant parts of the
  system to update grub2 afterwards:

  sudo mount /dev/sdaX /mnt (where X is the linux partition number found by fdisk -l before)
  sudo mount --bind /dev /mnt/dev
  sudo mount --bind /proc /mnt/proc
  sudo mount --bind /sys /mnt/sys

  sudo chroot /mnt.

  #Then first run
  dpkg-reconfigure grub-pc, 
  #telling it to leave grub on sda0, that is the MBR (master boot record)
  #in order to remove possible traces of old grub legacy versions

  #Then run
  gedit /etc/default/grub
  #and uncomment the line "GRUB_DISABLE_LINUX_UUID=true" (without quotation marks). Save the file
  #in order to replace the references to the UUIDs by label identifiers as shown above after the update of the next step will have #been executed. The reasons why the UUIDs may fail to work have been explained elsewhere; if You manage to do so, You #may as well according to this advice try to add one empty file as  inode [sudo mount /dev/sdaX /mnt] & [sudo touch
  #/mnt/empty_file] to solve the problem. The label IDs will need to be updated by update-grub2 in case of any partition changes!

  #Run
  sudo update-grub2
  #to apply the change in the grub default file (described in the step before) on other grub system files

  #Then first leave chroot by
  ctrl-d
  #and sucessively unmount the system data mounted before by (step 1 to 3, unmounting first /dev, then /proc, then /sys)
  sudo umount /mnt/[dev] [proc] [sys]
  #and finally (step 4)
  sudo umount /mnt

  Reboot. In my case this solved the problem

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