Can't find LVM root dropped back to initramfs

Question

When I boot up I get a screen saying:

Gave up waiting for root device

Then it lists common problems:

ALERT! /dev/mapper/ubuntu--vg-root does npt exist. Dropping to a shell!

Then I get an initramfs prompt.

Is this fixable without a backup?

I can't remember exactly what I did to make this stop working...

(My hard disk is NOT encrypted.)

Answer 1

Try a temporary workaround

In initramfs prompt type:

vgchange -ay

Sample output:

logical volume(s) in volume group "vg1000" now active

Followed by:

exit

If you have a LVM snapshot of root partition, that's a bug #360237. I solve this issue removing/deleting that snapshot.

If not your case, try fix doing this.

Another related bugs: #1396213, #29858, #1163406

Answer 2

Ubuntu's LVM autodetect didn't work at all for me either. To fix it, I made a script in

/etc/initramfs-tools/scripts/local-top/forcelvm

with the following contents:

#!/bin/sh
PREREQ=""
prereqs()
{
   echo "$PREREQ"
}
case $1 in
prereqs)
   prereqs
   exit 0
   ;;
esac
. /scripts/functions
# Begin real processing below this line

# This was necessary because ubuntu's LVM autodetect is completely broken. This
# is the only line they needed in their script. It makes no sense.
# How was this so hard for you to do, Ubuntu?!?!?
lvm vgchange -ay

Then did

# chmod +x `/etc/initramfs-tools/scripts/local-top/forcelvm`

for good measure and

# update-initramfs -u -k all

That fixed everything, while persisting after a system update.

Answer 3

1. Backup

   /usr/share/initramfs-tools/scripts/local-top/lvm2
   

2. Edit

   /usr/share/initramfs-tools/scripts/local-top/lvm2
   

3. Between modprobe -q dm-mod and activate_vg "$ROOT" add this line to initialize your lvm:

   lvm vgchange -ayactivate_vg "$ROOT"
   

4. Rebuild your initramfs:

   sudo update-initramfs -u
   

5. Rebuild your grub cfg:

    sudo update-grub
   

Enjoy! :-)