How to wipe a HD?

[Bruno Wolff III]

> > If you don't care about deleting all the data, a much easier way is:
> > 
> > dd if=/dev/zero/ of=/dev/hda
> > 
> > It will run for awhile (without a progress bar) and then stop.  Check 
> > the man pages if you want to check the progress of the wipe.
> > -ben
> 
> I've tried the dd route, and while I didn't do a detailed test to see if
> everything was wiped bit-by-bit, I did find that the disk was completely
> unusable.  I did this while performing some backup testing.  When I was
> done, although the system was still running, there weren't any disk-based
> commands anymore!  This likely will not meet official standards for "true"
> deletion of data (as shred tries to do) but it will go very far.

It will write over all of the addressible blocks on the drive. You won't
have access to remapped sectors. You won't get rid of trace magnetization
that would allow someone to see what data was stored on the drive in the past.
Unless you have very high value information on the drive this should be good
enough.

> If your desire is to remove information from a failed drive, there's always
> the bulk-tape-eraser-to-the-disk-drive technique.  A strong permanent magnet
> will help too!  I've done this on defective drives on which I can't run any
> commands, but only on drives I know to be defective.  I would not do this on
> a disk I wanted to use again.

If the data is high value, it is probably better to destroy the drive rather
than RMA it.

Another option is to use strong encryption when writing to the drive. Then
after wiping the disk, expensive data recovery techniques will provide
extremely little information about your data.