Comments on: What UUIDs Are and How To Use Them in Ubuntu

By: Mike Christianson

Mike Christianson — Mon, 02 Mar 2009 07:05:20 +0000

Thanks for the info. It came in handy after repartitioning my two drives.

By: Wim

Wim — Wed, 28 Jan 2009 20:07:14 +0000

If these UUIDS are considered unique then why the heck do I get the same UUID all of a sudden. For some weird reason some of the UUIDs got screwed up.

sudo blkid
/dev/sda1: UUID="cde9bfc0-4c4f-405d-8729-95c0624cd3b3″
/dev/sda2: TYPE="swap" UUID="19233dcb-6ae3-4b5f-a926-39e1909689c6″
/dev/sdb1: UUID="cd79f6ab-6770-4e6c-a4ad-15db909abe02″
/dev/sdc1: UUID="e7041c14-3952-4af6-8d98-fddc8e9313b9″
/dev/sdd1: UUID="7bfd287a-9bab-4ef0-9e35-8931dba74f91″
/dev/sde1: UUID="740b0350-af69-4d23-83ec-31b6f6e8b4ce"
/dev/sdf1: UUID="740b0350-af69-4d23-83ec-31b6f6e8b4ce"

Why oh why are these id's NOT unique?
Reason #1 is not a correct argument if I look at this

By: Anon

Anon — Fri, 28 Nov 2008 17:37:11 +0000

UUIDs suck big time. They are hard to find out, keep changing all the time and GRUB doesn't use them. Linux developers are just insane to have introduced this.

By: Embedded

Embedded — Sat, 07 Jun 2008 19:52:23 +0000

Speaking of UUID and Grub on SuSE the Grub boot knows about UUID as does /etc/fstab.

If you clone a Hard Drive better edit these for the new one because they will NOT be right on it eg. Toshiba 100GB hard drive to Toshiba 320GB hard drive. Best to rename all to sda0-whatever from UUID. (you can do that on the original too)

Been There done that.

By: Gleb Reys

Gleb Reys — Sat, 24 May 2008 00:53:24 +0000

Thanks for a really useful comment – good to know, especially BEFORE adding new drive to one's PC

By: Eugene Morozov

Eugene Morozov — Fri, 23 May 2008 20:31:35 +0000

Hey Gleb!
I have a minor addition to your post. GRUB doesn't know anything about UUIDs. The only UUIDs in the GRUB configuration are in the kernel command line – they aren't parsed by GRUB but passed directly to kernel after it is loaded.

Unfortunately, grub still uses BIOS drive numbers (see the line "root hd(0, 1)"). 0 means the first BIOS drive, and 1 means second partition on that drive. So if you add a new hard drive to your system, BIOS may renumber the disks (this is likely if you add PATA disk to a bunch of SATA disks, or vice versa) and the system will become unbootable.

In this case, type 'e' key when grub is loaded, select line 'root hd(0,1)' (or whatever drive and partition numbers you have), type 'e' again, and try increasing or decreasing drive number. Press Enter when you finished editing, and then press 'b'. If you guessed the BIOS drive number, the system will boot fine – no need to alter other parameters because kernel will find the root filesystem by UUID.

By: Gleb Reys

Gleb Reys — Tue, 13 May 2008 11:02:14 +0000

Hey Stan,
Thanks for a comment!

Yes, labels are available in Ubuntu as well, and they're somewhat better than using device names, but still not as good as UUIDs.

By: stan

stan — Tue, 13 May 2008 10:53:41 +0000

redhat based distro's use labels instead of uuid's. this is such a bad way to do things…. uuid's simply rock.