The hexadecimal number is probably the drive
UUID.
More and more distros are going to the UUID to prevent problems with the way devices are mounted at boot since most devices are all marked as scsi devices (i.e. /dev/sdXX). There is no longer a distiction between IDE and SATA drives in newer kernels, so the UUID helps keep that order so that /dev/sda always boots up as /dev/sda, even if you plug in an external drive before boot.