How to find Universal Unique Identifier of a disk?

See if this helps

http://www.engadget.com/2013/07/25/mac-101-finding-your-macs-uuid/

The solution proposed by Sparkleberry only gives you the UUID of the Mac itself, it does not give you the UUID of each volume/disk.

Try instead the following -

• Go the the Apple Menu and select About This Mac
• Then click on System Report
• Then on the left select Storage

This will list all the disks and volumes currently mounted and each will when select show in the bottom right section a Volume UUID.

On El Capitan, there are 3 UUID associated with a volume/partition:

• Core Storage
  • PV UUID
  • LV UUID
• Disk Partition ID

All graphical approaches will show just the Core Storage related UUID. In the Terminal, system_profiler SPStorageDataType command will only report Core Storage UUID. The diskutil info /dev/disk0s2 will report all 3 of the formats. If you don't want to scroll, the following command will get the real UUID which is first in the listing, and accordingly, I tell egrep to get the first match so it doesn't capture the Core Storage UUID values.

Terminal:

Only type the blue text:

$ diskutil info /dev/disk0s2 | egrep -om1 "([A-Z0-9]{8}.[A-Z0-9]{4}.+$)"

If you want the PV and LV UUID values for the Core Storage only, then change the m1 to m2 in egrep.

In John's advice, look for the Physical Volume UIDD

Disk Utility → Select Disk/Partition → click "Info".