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

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 2

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 3

1

In initramfs, type:

     #/sbin/lvm vgchange -a y
     #vgchange -a y
     #exit

If you're unable to solve the issue, type this:

ls /dev/mapper Now, you should have found root (like /dev/vgname/lvname).

reboot And then select a kernel on the screen and select e to edit and paste a root value (like /dev/vgname/lvname) at:

/boot/vmlinuxxxxx root=uuid/dev/xxx. Then, finally, press Ctrl+X to boot.

If problem repeats when reboot the server

go to

#/boot/grub/grub.cfg at /vm/vmlinuz root=write your full lv path

if problem not fixed try fix initramfs as below

1.Go to server terminal

  # sudo rmmod floppy

   #echo "blacklist floppy" | sudo tee /etc/modprobe.d/blacklis-floppy.conf

#dpkg-reconfigure initramfs-tools #update-initramfs -u #update-grub #reboot Execute this

#/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 lvm vgchange -ay Then do

   # chmod +x `/etc/initramfs-tools/scripts/local-top/forcelvm`
   # update-initramfs -u -k all

take backup of lvm2

    #apt-get install lvm2
    #cp /usr/share/initramfs-tools/scripts/local-top/lvm2  /tmp

Edit lvm2

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

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

lvm vgchange -ayactivate_vg "$ROOT" if you not find this line

write below two line at the end of the file above exit 0

       #lvm vgchange -ayactivate_vg "$ROOT"
       #activate_vg="$ROOT"

save the file then

        #update-initramfs -u
        #update-grub
        #reboot

Answer 4

For some of you it might be a problem in your grub.cfg:

Stumbled about the same problem (root not found as lvm volume groups were not activated by initrd) today on 18.04. I figured out that the volume groups are automatically activated if you specify your root device in the "grub.cfg" via device name

linux   /vmlinuz root=/dev/mapper/vg-root

where as they are not automatically activated if you specify it per UUID

linux   /vmlinuz root=UUID=abcd-[...]

Thus there had to be some script in initrd which contains this logic.

Answer 5

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! :-)