Configure separated GRUB to run Linux from LVM ddrescued device

Question

I got new 120GB SSD and I want to restore my Linux Mint from my ddrescued /dev/mapper/mint--vg-root

I splited SSD to 500MB sdb1 Ext4 and 119GB sdb2 LVM as it was before crash.

Then I created mint-vg group and made root volume. Restored ddrescued Mint image to mint--vg-root.

Then I installed GRUB to mounted sdb1 with this:

sudo grub-install --root-directory=/media/user/mouted_sdb1 /dev/sdb

Now when I boot from SSD I get GRUB black screen I tried how-rescue-non-booting-grub-2-Linux, but GRUB says, that my lvm partitition has unknown filesystem:

grub> ls (hd0,msdos <TAB>

Available partititions are

Partitition hd0,msdos1: Filesystem type ext* - Last modified .....

Partitition hd0,msdos2: No known filesystem detected - Partitition start at ....

I tried boot-repair with GUI. It lists my mapper/mint--vg-root, but after repair my mint not in list of systems. Mark mapper/mint--vg-root as default requires LiveCD.

Tried to:

insmod lvm

In grub console without result (still no known):

Tried this:

sudo grub-mkconfig -o grub.cfg

It says that /dev/mapper/mint--vg-root is found, but in grub.cfg is no record about this.

How make GRUB to load my Mint from lvm?

UPDATE:

Here some Boot Info Summary from my old system and from new. In new I have no "Extended partitition"

OLD:

sdb1:

File system:       ext2

Boot sector type:  -

Boot sector info: 

Operating System:  

Boot files:        /grub/grub.cfg /grub/i386-pc/core.img

sdb2:

File system:       Extended Partition

Boot sector type:  -

Boot sector info: 

sdb5:

File system:       LVM2_member

Boot sector type:  -

Boot sector info: 

mint-vg-root:

File system:       ext4

Boot sector type:  -

Boot sector info: 

Mounting failed:   mount: wrong fs type, bad option, bad superblock on /dev/mapper/mint--vg-root,
   missing codepage or helper program, or other error
   In some cases useful info is found in syslog - try
   dmesg | tail or so.

mint-vg-swap_1:

File system:       swap

Boot sector type:  -

Boot sector info: 

new Boot Info Summary:

sdb1:

File system:       ext4

Boot sector type:  -

Boot sector info: 

Operating System:  

Boot files:        /boot/grub/grub.cfg /boot/grub/i386-pc/core.img

sdb2:

File system:       LVM2_member

Boot sector type:  -

Boot sector info: 

mint-vg-root:

File system:       ext4

Boot sector type:  -

Boot sector info: 

Operating System:  Linux Mint 18.1

Boot files:        /etc/fstab

SOLVED with how-rescue-non-booting-grub-2-Linux with some modifications in GRUB console:

grub> set root=(lvm/mint--vg-root)
grub> linux (hd0,msdos1)/boot/vmlinuz-4.4.0-112-generic root=/dev/mapper/mint--vg-root
grub> initrd (hd0,msdos1)/boot/initrd.img-4.4.0-112-generic
grub> boot

After boot I ran boot-repair and it works now.

Answer 1

SOLVED with how-rescue-non-booting-grub-2-Linux with some modifications in GRUB console:

grub> set root=(lvm/mint--vg-root)
grub> linux (hd0,msdos1)/boot/vmlinuz-4.4.0-112-generic root=/dev/mapper/mint--vg-root
grub> initrd (hd0,msdos1)/boot/initrd.img-4.4.0-112-generic
grub> boot

Where (hd0,msdos1) is sdb1.

After boot I ran boot-repair and it works now

Also I fixed UUIDs in /etc/fstab, because my boot /folder is mounted from (hd0,msdos1) partitition. There are all files like vmlinuz... and initrd.img to boot properly.

Answer 2

i did the same but totally avoided non lvm pointers:

grub> set root=(lvm/mint--vg-root)
grub> linux /boot/vmlinuz-4.4.0-112-generic root=/dev/mapper/mint--vg-root
grub> initrd (hd0,msdos1)/boot/initrd.img-4.4.0-112-generic
grub> boot

best regards, alex

Answer 3

In the event you are using efi and not bios boot mode, the commands are just slightly different. You may need to look for the efi partition with the kernels in addition to the root lvm partition. I found the intrd image and vmlinuz in the efi partition (hd0,gpt1) for my system.

grub> ls
(hd0) (hd0,gpt1) (hd0,gpt2) (hd1) (hd1,gpt1) (lvm/mint_vg_root) (lvm/mint_vg_var)

grub> ls (lvm/mint_vg_root)/boot/
./ ../

grub> ls (hd0,gpt1)/
./ ../ efi/ vmlinuz-5.13.0-7620-generic initrd.img-5.13.0-7620-generic

grub> set root=(lvm/mint_vg_root) 
grub> linuxefi (hd0,gpt1)/vmlinuz-5.13.0-7620-generic root=/dev/mapper/mint_vg_root
grub> initrdefi  (hd0,gpt1)/initrd.img-5.13.0-7620-generic
grub> boot