[Bug 1070485] Re: Ubiquity switches sda and sdb in Grub configuration, causing boot failure

[Adam Conrad]

Actually, a bit of reading suggests that remapping the boot drive (even
a USB stick) to 80H is the right thing to do anyway, so is probably the
behaviour of most BIOSes, and probably not the cause of this bug.  I'll
leave it to others to debug more formally at some point, though.

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https://bugs.launchpad.net/bugs/1070485

Title:
  Ubiquity switches sda and sdb in Grub configuration, causing boot
  failure

Status in “ubiquity” package in Ubuntu:
  Confirmed

Bug description:
  When I install *buntu 12.10 by means of a Live USB (USB memory stick),
  Ubiquity often (not always) wrongly identifies the memory stick as
  'sda' and the hard disk as 'sdb'.

  Ubiquity then installs *buntu 12.10 nevertheless on the hard disk with
  nearly all configuration right, namely the hard disk as 'sda'. With
  one fatal exception: Grub. Grub is configured to boot from 'sdb'.

  Upon first boot from the hard disk (with the USB stick removed), Grub then of course spawns this error:
  error: unknown filesystem
  grub rescue>

  When I found out what the cause was, it was easy to repair: simply boot up the PC by means of a *DVD* and point Grub to 'sda' by means of this terminal command:
  sudo mount /dev/sdaX /mnt && sudo grub-install /dev/sda --root-directory=/mnt
  (where the X in sdaX needs to be replaced by the partition number of the root partition)

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