HOWTO get a disk UUID

udev now uses disk UUIDs for consistent mounting, so you probably see something like this is /etc/fstab:

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# /dev/sda1
UUID=27EEEEEE-CFAF-4608-8036-FFFFBAEEEEEE /          xfs     relatime,errors=remount-ro 0       1   

So how can you map the /dev/sd* structure to UUIDs? Simple:

~$ ls -lh /dev/disk/by-uuid/
total 0
lrwxrwxrwx 1 root root 10 2010-03-20 14:15 27EEEEEE-CFAF-4608-8036-FFFFBAEEEEEE -> ../../sda1

If the list is out of date you can refresh it by restarting udev:

sudo /etc/init.d/udev restart

The disktype utility can also help:

~$ sudo disktype /dev/sda

--- /dev/sda
Block device, size 298.1 GiB (320072933376 bytes)
DOS/MBR partition map
Partition 1: 298.1 GiB (320070288384 bytes, 625137282 sectors from 63)
  Type 0x83 (Linux)
  XFS file system, version 4
    Volume name ""
    UUID 27EEEEEE-CFAF-4608-8036-FFFFBAEEEEEE
    Volume size 296.6 GiB (318523899904 bytes, 77764624 blocks of 4 KiB)

And you can also use 'vol_id' (now deprecated in favour of 'blkid') to print the UUID:

~$ sudo vol_id /dev/sda1
ID_FS_USAGE=filesystem
ID_FS_TYPE=xfs
ID_FS_VERSION=
ID_FS_UUID=27EEEEEE-CFAF-4608-8036-FFFFBAEEEEEE
ID_FS_UUID_ENC=27EEEEEE-CFAF-4608-8036-FFFFBAEEEEEE
ID_FS_LABEL=
ID_FS_LABEL_ENC=
ID_FS_LABEL_SAFE=