"The Linux kernel is a restless beast, and must continally
evolve and change. Especially in ways that mystify us poor end
lusers. A recent wrinkle, as of kernel version 2.6.20, is changing
the /dev names for ATA devices, so that all ATA and SCSI devices
are named /dev/sd*. This is a result of using the shiny new libata
subsystem. In the olden days PATA (also called IDE) hard drives and
ATAPI devices (CD/DVD, tape drives) were /dev/hd*, and SCSI and
SATA devices were /dev/sd*.
"However, not all Linux distributions default to using libata.
*buntu Feisty and Gutsy are all over the map; some versions of them
use the new naming convention, some don't, and I haven't figured
out which ones, or why. You can see how your own system handles
these names with a couple of simple commands..."