Ubuntu: ALERT! /dev/mapper/localhost-root does not exist. Dropping to a shell!

Question

I'm currently using Ubuntu Maverick, and whenever I try to use a kernel newer than 2.6.32-21, I get this message:

ALERT!  /dev/mapper/localhost-root does not exist.  Dropping to a shell!

Does anyone have a clue what could be wrong? I'm not able to come up with anything.

The entry in /etc/fstab looks like this:

# / was on /dev/mapper/localhost-root during installation
UUID=dd17c070-dc6a-4b91-bb3c-458fd5f11342 / ext3 relatime,errors=remount-ro 0 1

The hardware details are here: http://cdgenp01.csd.toshiba.com/content/product/pdf_files/detailed_specs/satellite_L305D-S5928.pdf

Answer 1

Are you compiling your own kernel? If so, you'll get this message if your root volume is on an LVM but necessary modules for LVM are not available either built-in to the kernel or on the initrd.

Answer 2

My boot configuration was borked in several ways, I guess because I fiddle with things too much. Here are the problems and solutions. Essentially all of these commands need to be run as root, so run sudo -s beforehand.

1) The boot process didn't support LVM. You can check this by running gunzip < /boot/initrd.img-2.6.35-27-generic | cpio -id and checking for sbin/lvm.

To fix: (you only need one of these, but both doesn't hurt)

apt-get install lvm2
dpkg-reconfigure lvm2

2) My swap partition wasn't mounting. You can check this with the free command. The swap-total should be non-zero.

To fix:

swapoff  -a
mkswap -f -L SWAP /dev/mapper/mymachine-swap_1 
blkid
vim /etc/fstab (change the UUID's to match the output of blkid)
swapon -a