[Gllug] Thoughts on secondhand server guide price

[Philip Hands]

On Wed, Jun 17, 2009 at 10:22:44AM +0100, John Hearns wrote:
> 2009/6/17 Jose Luis Martinez <jjllmmss at googlemail.com>
> 
> >
> > I also would be interested to know if anybody can cite specific
> > examples of disks from which data has been  recovered once they have
> > been overwritten.
> >
> >
> 
> Not from an overwritten disk, however I once recovered a PC dumped in the
> bins where I live. Complete with letters to the bank manager on the hard
> drive.
> 
> Regarding secure deletion of data, government secure sites don't let you
> have failed hard drives back - the drives are sent to a site where they are
> destroyed.

Quite -- I believe that it's often the case that embassy machines have
a thermite pack above them in case of the need for a rapid exit.  Dropping
a load of molten iron on the platters is liable to do the trick, eh?

Personally, I use shred (from coreutils) on running systems, and DBAN
for nuking machines (typing autonuke at the boot: prompt and say goodbye
to your data, as long as the drive controller is supported):

  http://www.dban.org/

Of course, if it's a failing disk, chances are it will have remapped
some blocks and anything you do to it that goes through normal channels
will not touch those old (broken) sectors, since the writes will go to
the remapped sectors instead -- someone that's able to take the disk to
bits and look at the surface, or put a diagnostic drive controller on
it might get some of that data off.

Of course, most of the original folklore about this was developed in the
days of MFM disks and before, when one could expect the tack on the disk
to be quite wide, and for the overwrite pass to miss the dead centre of
that magnetic path, leaving a fuzzy version of the previous data.

The data density on modern drives, and the cleverness of the coding
schemes makes that sort of thing much less feasible, hence the emerging
opinion that simply writing a lot of zeros is liable to be enough,
especially if the most secret thing on the disk is some old mail logs
and there are not black helicopters circling your building.

Cheers, Phil.
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