ubuntu 18 lvm move to another disk (also lvm) - backup and restore

Question

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.

• Emmanuel Rosa: On which partition is /boot located? /dev/sdb2 perhaps?
• gene: Yes, it is on /dev/sdb2. I've edited the question to add more info.

Answer 1

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