[clug] Secure Erase of disks/drives

[Michael Cohen]

On Tue, May 08, 2007 at 06:09:18PM +1000, Alex Satrapa wrote:
> If the feature size has gone down an order of magnitude, doesn't that  
> mean the detection hardware has improved by a similar margin? If the  

Thats absolutely correct - the ability to detect magnetic modulation on such
small feature size has obviously also improved - otherwise you could never read
the stuff.

> technology is viable to the point of mass production, there is  
> certainly specialist technology out there that is an order of  
> magnitude more accurate. There has to be as part of the development,  
> testing and quality control process for the mass-produced item.

Yes but that is different from detecting _overwritten_ material which requires
the detection techniques to be _significantly_ better than the standard read
heads. When you want to read overwritten data you are operating in the domain
which is outside the designed specification. Its a big leap to make the
assumption that its possible to read overwritten stuff just because you can
read non overwritten data. If you are pushing technology to its limits in terms
of detecting legitimately written data, you are really clutching at straws to
be able to detect overwritten material reliably.

It just makes sense - if there was an easier way to read say 1 or 2 time
overwritten data (say by some great dsp technique/better heads etc) - your
driver storage could just be increased by a factor of 2 with little cost.

Michael.