NO program run on the computer can necessarily write to drives in
parallel, because the disk controller cannot necessarily write to drives
in parallel (for example, a master and slave drive on the same IDE
channel cannot be written to in parallel; at any given time you can only
access one drive or the other, they are both on the same controller and
even the same cable).

That's where using a command internal to the drive has an advantage; you
tell the drive to wipe itself, and while the operation may then take a
long time, everything happens within the drive. No further interaction
with the controller (the IDE or SATA or even SCSI controller) is required.

That doesn't mean that any given program using the "wipe drive" command
will necessarily support doing multiple drives in parallel, but it's at
least conceptually possible. However, doing it through the controller
may be literally impossible, unless each drive is on a totally separate
controller and is using bus mastering DMA.


S.Lewis wrote:

I've got DBAN, but again I don't believe it will wipe drives in parallel,
only sequentially. I'll have another look at their readme....

Don't need it for USB or 1394, thankfully.