Ubuntu losing root filesystem on first boot

[Erik Bixby]

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On 11/15/06, eric(c) <ericlists at gmail.com> wrote:
> Altho I've been using Linux on and off for a few years now, I still consider
> myself a newbie.  I THINK what's going on here is a configuration issue,
> where it should be loading /dev/hda, not /dev/hde.  But I don't want to just
> start changing configs around without really knowing what I'm doing and
> digging a deeper hole.

I recently dealt with pretty much the same issue.  I had installed
Ubuntu with my CD-ROM reader on the same IDE bus as my hard drive.
After I finished my install I removed the reader, and the drive
refused to boot.  What appears to have happened, in my case, was that
both drives were set to cable select, and the CD-ROM settled on the
master and the hard drive on slave.  So, my hard drive was /dev/hdb
during the install, but became /dev/hda after the CD-ROM reader was
removed.  As a result, I had to edit my /boot/grub/menu.lst file to
reflect this change.

If I were you, I would try booting off the install CD and editing that
file.  It's easy enough to make a backup if you're concerned about
making a mistake and blowing something up:
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst.backup

Should you decide that you've messed up your editing:
sudo cp /boot/grub/menu.lst.backup /boot/grub/menu.lst

Do do the actual editing:
sudo vi /boot/grub/menu.lst

If you're not familiar with vi, you can substitute gedit if you're
using Ubuntu proper, or kate if you're using Kubuntu (as Kubuntu
doesn't have gedit installed by default).

The boot drive should be /dev/hda, if it's the master of the first IDE
channel on the system.  The partition number is likely correct.  If
you're experiencing a problem similar to what I had, you should be
able to simply change the "e" to an "a" and be good to go.

Good luck!
-Erik