grub2: VFS: Unable to mount root fs

[Simon Brandmair <sbrandmair@gmx.net>]

Hi everyone,

I upgraded grub to grub2 (squeeze) and at first I couldn't boot my linux 
kernel (2.6.32), which work fine with the old grub. The boot process 
stopped with the following messages: "VFS: Unable to mount root fs on 
unknown-block(0,0)".

After some research, I figured that the root fs is not set correctly in /
boot/grub/grub.cfg. The root fs was defined with a uuid string, which I 
confirmed as correct. After altering the uuid string to /dev/sda2, linux 
would boot normally.

Since grub.cfg is not supposed to be edited, I added to /etc/default/grub
(thanks to https://help.ubuntu.com/community/Grub2):
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to
# Linux
GRUB_DISABLE_LINUX_UUID="true"

and then ran `update-grub`.

I thought this might be helpful for others running into the same problem. 
Also, any idea why the (again: correct) uuid string didn't work? I have 
two other systems with a similar set-up and defining the root fs with uuid 
works just fine.

Cheers,
Simon