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My boot disk is /dev/sda. I've used gdisk to create identical partition table on WD disk /dev/sdb as shown below.

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            4095   1024.0 KiB  EF02  BIOS boot partition
   2            4096         2101247   1024.0 MiB  8300  Linux filesystem
   3         2101248       234438655   110.8 GiB   8300  Linux filesystem

I've restored /dev/sdb3 partition using fsarchive. I've also ran "sudo grub-install /dev/sdb".

When I try and boot from /dev/sdb I get:

error: no such device : ce2....
unknown file sytem ...
grub rescue>

Assuming I never use these disks together on the same machine - what else do I need to do to be able to boot from the /dev/sdb? Should I change the UUID of the restored disk to something unique? Should I be able to mount /dev/sdb2 on the original system? (I can still boot that system.)

EDIT1 - output of lsblk:

NAME                        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop0                         7:0    0  88.5M  1 loop /snap/core/7270
loop1                         7:1    0  88.4M  1 loop /snap/core/7169
sda                           8:0    0 111.8G  0 disk 
├─sda1                        8:1    0     1M  0 part 
├─sda2                        8:2    0     1G  0 part /boot
└─sda3                        8:3    0 110.8G  0 part 
  ├─ubuntu--vg-ubuntu--lv-real
  │                         253:0    0    24G  0 lvm  
  │ ├─ubuntu--vg-ubuntu--lv 253:1    0    24G  0 lvm  /
  │ └─ubuntu--vg-lvsnap_me5_201906251023
  │                         253:3    0    24G  0 lvm  
  └─ubuntu--vg-lvsnap_me5_201906251023-cow
                            253:2    0    15G  0 lvm  
    └─ubuntu--vg-lvsnap_me5_201906251023
                            253:3    0    24G  0 lvm  
sdb                           8:16   0 931.5G  0 disk 
├─sdb1                        8:17   0     1M  0 part 
├─sdb2                        8:18   0     1G  0 part 
└─sdb3                        8:19   0 110.8G  0 part 

EDIT2: After doing the "grub-install" in a @Emmanuel Rosa (correct) way from below I get further, but still fail:

madm ...
    WARNING: failed to connect to lvmetad. Falling back to device scanning.
    volume group "ubuntu-vg" not found.
    Can not process volume group ubuntu-vg.
Done.

But this might be a separate question? If no body chimes in in a next 7 days - I'll accept his answer.

  • On which partition is /boot located? /dev/sdb2 perhaps? – Emmanuel Rosa Jul 21 at 10:06
  • Yes, it is on /dev/sdb2. I've edited the question to add more info. – gene Jul 21 at 14:15
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Since you're installing GRUB to a different disk, you need to tell grub-install where the /boot partition on your new disk is. Here's an example (run as root):

mount /dev/sdb2 /mnt
grub-install --boot-directory=/mnt /dev/sdb
umount /mnt

See https://www.gnu.org/software/grub/manual/grub/html_node/Invoking-grub_002dinstall.html#Invoking-grub_002dinstall

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