[Ti] OT Erasing a hard drive

[Bill Palmer]

>
> You can use the options tab in Drive Setup to select "Zero All Data".
> You don't have to use Symantec's anything. Doing that writes zeroes to
> all data sectors on the HD. You can't erase anything more than that. :)
>
> Rick Banuelos

You might think so, but you'd be wrong.  Sufficiently motivated (and funded), it is
still possible to recover the data off a disk drive that has been overwritten.  The
data is stored in analog form, and minute traces of the previous state of the bits can
be recovered by small-signal analysis.
There's a government standard for  securely erasing disk drives that have been used to
store sensitive materials, and my understanding is that it involves repeatedly writing
a number of different patterns designed to destroy those traces.

Here's some reading on the topic:

http://www.cs.auckland.ac.nz/%7epgut001/pubs/secure_del.html