How to wipe a HD?

Robert P. J. Day rpjday at mindspring.com
Sat Apr 23 18:00:21 UTC 2005


On Sat, 23 Apr 2005, Bruno Wolff III wrote:

> > > 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.

another solution is to boot from a CD and just rewrite the entire
drive several times using "dd" -- enough times to wipe that trace
magnetization.  start with

  # dd if=/dev/zero of=/dev/hda ...

now, it's too bad there's no /dev/ones.

  but you could also keep overwriting with /dev/random.  after a
while, i'm pretty sure there won't be much salvageable from the drive.

rday




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