[ale] HELP! Mint machine is booting from the wrong hard drive

[Phil Turmel]

On 07/02/2013 11:15 PM, Ron Frazier (ALE) wrote:
> Hi all,
> 
> One of my machines is running Mint 13 (based on Ubuntu 12.04).  The
> machine has two hard drives, a 320 GB hard drive on /dev/sda and a 500
> GB hard drive on /dev/sdb.  The 500 GB drive is for backup purposes
> only.  Tonight, I made an exact clone (as far as I know) of the 320 GB
> hdd over to the 500 GB hdd with clonezilla.  The 500 GB hdd is still
> attached.

The problem is that you made an *exact* clone.  Modern distros use the
UUID or LABEL embedded in a filesystem to find the necessary partitions
during boot (to avoid issues with hot-pluggable drives).  If you clone
partitions, both will have that metadata, and your boot process becomes
random.

> My bios is set to boot from the 320 GB drive (/dev/sda).  Once I boot,
> the grub menu asks if I want to boot Mint on /dev/sda2, which is
> correct.  I select that, but, when the system comes up, I find that the
> 500 GB hdd (/dev/sdB2) is the one that's mounted, and that's not what I
> want.
> 
> Can someone tell me why this is happening and how to prevent it without
> physically unplugging the drive?

Change the label and uuid on the partition(s) on one of the drives, then
change /etc/fstab within that one to point to its own label/uuid.  The
utilities needed vary with filesystem type, but it would be "tune2fs"
for anything in the "ext" family.

Use a rescue CD or thumb drive so you have total control over temporary
mounts.  Check your work with "blkid".

Phil