Ubuntu 20.04 Backing up disk using GParted how are UUIDs handled?

[Bo Berglund]

On Wed, 04 Dec 2024 21:38:25 +0100, Nils Kassube via ubuntu-users
<ubuntu-users at lists.ubuntu.com> wrote:

>On 04.12.24 Bo Berglund wrote:
>> My Ubuntu 20.04.6 LTS Server has a single disk that is a bit too small, so I
>> figured that I should use GParted standalone to copy its partitions to a new
>> bigger drive.
>> I have GParted on a bootable Ventoy USB stick.
>>
>> And while doing that I might only bring along the server and its used
>> partitions.
>> I might also enlarge/create a data partition on the copy using the extra space
>> on that drive.
>>
>> But my /etc/fstab file has these entries:
>>
>> UUID=ec0e8708-8a6a-4bbf-93ba-0a09b1e2ddc1 / ext4 errors=remount-ro 0 1
>> UUID=a77b40db-2377-4d25-b304-8d233664d1ca none swap sw 0 0
>> UUID=42BE-49BB  /boot/efi vfat umask=0077 0 1
>> UUID=389c6db9-3256-47ed-b67f-c11c76eed17f /home ext4 nodev,nosuid 0 2
>> UUID=fb4a08b7-378e-42eb-9b7a-2c7b4f85cd06 /var/lib/svn ext4 nodev,nosuid 0 2
>>
>> As you can see the partitions that are mounted use UUID values to define which
>> is mounted where.
>>
>> Now to the questions:
>>
>> 1) UUID
>> If I copy the partitions themselves to another bigger drive as a backup or for
>> migration, will the UUID of the partitions stay the same or are they
>> re-generated so the source and destination can be told apart?
>
>The UUID will be the same because it is a value inside the partition you copy.
>
>> 2) Use of new disk
>> If UUIDs stay the same, can I then put the bigger drive into the PC and boot it
>> up and expect Ubuntu to come alive?
>> That would essentially make it a backup drive copy....
>
>That will only work reliably if you remove the smaller disk. If you have two partitions 
>with identical UUIDs the system doesn't really know which partition is the wanted one. 
>If you want to use both disks in the same machine, you should change the UUID of one 
>of the partitions.
>

Thanks for the UUID clarification!


-- 
Bo Berglund
Developer in Sweden