How can you give a disk and a new UUID?

Question

I just used sfdisk to clone my partition table to a new disk,

sudo sfdisk -d /dev/nvme0n1 > /tmp/part.txt
sudo sfdisk /dev/nvme1n1 <  /tmp/part.txt

However, now both drives have the same uuid. How can I fix that and generate a new UUID for device with the cloned partition table?

The number that are duped can be seen with sudo fdisk -l. You can see the "523436E9-4DA5-474F-87CA-D784E4BF345D" is shared as a common "Disk identifier"

Disk /dev/nvme1n1: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
[...]
Disklabel type: gpt
Disk identifier: 523436E9-4DA5-474F-87CA-D784E4BF345D
[...]


Disk /dev/nvme0n1: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
[...]
Disklabel type: gpt
Disk identifier: 523436E9-4DA5-474F-87CA-D784E4BF345D

You can also see a shared UUID with,

❯ lsblk -o +uuid
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS UUID
nvme1n1     259:0    0  1.8T  0 disk             
├─nvme1n1p1 259:2    0  512M  0 part             
└─nvme1n1p2 259:3    0  1.8T  0 part             7d78ed4b-e4aa-4270-853d-6489ea4d6c54
nvme0n1     259:1    0  1.8T  0 disk             
├─nvme0n1p1 259:4    0  512M  0 part /boot/efi   1D40-E385
└─nvme0n1p2 259:5    0  1.8T  0 part /           7d78ed4b-e4aa-4270-853d-6489ea4d6c54

On the partition "7d78ed4b-e4aa-4270-853d-6489ea4d6c54" is shared?

Are you asking about the GPT PARTUUID or the filesystem UUID? If the latter, which filesystem? — muru, Jul 31 '23 at 07:53
could also be the Disk identifier (GUID) (which sfdisk calls the `label-id`) — Jaromanda X, Jul 31 '23 at 08:06
You could just remove the UUIDs from the sfdisk dump before applying it on the new disk. — Paul Pazderski, Jul 31 '23 at 08:13
[This question](https://unix.stackexchange.com/q/12858/258991) includes answers on how to change the PARTUUIDs and the PTUUID using `fdisk`, and also how to change the UUIDs of many filesystem types. — telcoM, Jul 31 '23 at 08:21
Oops, forgot to clarify: Disk identifier seems to be another name for the PTUUID, at least on GPT disks. `fdisk` just calls it the "disk GUID". And unfortunately the OP did not specify which type of partition table the question is about - although the presence of NVMe devices makes GPT more likely. — telcoM, Jul 31 '23 at 08:29
Was partition table so complicated that just manually recreating it was more complicated than trying to change UUIDs & GUIDs? And if drive not exactly same size, you also have to move backup partition table to end of drive, not sure if sfdisk does that with a copy or not. — oldfred, Jul 31 '23 at 14:59

Evan Carroll · Answer 1 · 2023-07-31T16:45:44.810

The device identifier UUID

I was able to change the UUID of disk with sfdisk,

sudo sfdisk --disk-id /dev/nvme1n1 $(uuidgen)
Disk identifier changed from 523436E9-4DA5-474F-87CA-D784E4BF345D to E15A552B-CD07-4332-B73C-E67765D11F4E.

The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Partition UUIDs

In order to give the partitions a new UUID with

sudo btrfstune -f -U $(uuidgen) /dev/nvme1n1p2

I had to first take the device offline by removing it from the raid1 array -- which because there were only two disks required first removing raid1,

sudo btrfs filesystem balance start -dconvert=single -mconvert=dup

Then I was able to remove the device,

sudo btrfs device remove /dev/nvme1n1p2 /

Then I had to create a btrfs filesystem on the device so I could use btrfstune

sudo mkfs.btrfs /dev/nvme1n1p2

Then I could change the partition uuid,

sudo btrfstune -f -U $(uuidgen) /dev/nvme1n1p2

But lsblk -o +uuid does not show the partition (nvme1n1p2)'s uuid, so I'm not sure what exactly is going on,

lsblk -o +uuid
NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS UUID
nvme1n1     259:0    0  1.8T  0 disk             
├─nvme1n1p1 259:2    0  512M  0 part             
└─nvme1n1p2 259:3    0  1.8T  0 part             
nvme0n1     259:1    0  1.8T  0 disk             
├─nvme0n1p1 259:4    0  512M  0 part /boot/efi   1D40-E385
└─nvme0n1p2 259:5    0  1.8T  0 part /           7d78ed4b-e4aa-4270-853d-6489ea4d6c54

How can you give a disk and a new UUID?

1 Answers1

The device identifier UUID

Partition UUIDs