drive wipe

Charles Curley charlescurley at
Thu Oct 23 14:55:18 MDT 2008

On Thu, Oct 23, 2008 at 11:46:46AM -0600, Steven Alligood wrote:
> Brian Beardall wrote:
>> On Thu, 2008-10-23 at 07:52 -0600, Aaron Toponce wrote:
>>> On Wed, Oct 22, 2008 at 11:58:15PM -0600, Dr. Scott S. Jones wrote:
>>>> What does one use to wipe a drive, what application? I have a few that I
>>>> need to clean up...and overwrite, to protect patient data.       
>>> dd if=/dev/zero of=/dev/hda
>>> Want to contest that the above command securely deletes data? See the
>>> following link, then get back to me:
>> The award money isn't even worth it. The best way would be to have the
>> FBI or CIA want the data off the disk. They'll spend what ever it takes
>> to invent the technology to get the data off. After all those two
>> probably have the best data recovery services this planet has to offer.
>> I'm not suggesting to do anything illegal to test their services though.
>> Brian Beardall
> I agree, the $500 is not worth the effort for these companies, all of  
> which will charge at least that for a Norton undelete level of recovery.  

The $500 wouldn't be. But the bragging rights might.

> The drive itself is only designed to read the most powerful magnetic 
> impression, not the lower level remains of old data.  A truly high end 
> firm, like the CIA or FBI would remove the platter from the drive housing 
> and use special equipment to read the differences under those
> zeroes.

Actually, all you do is pull the PCB from the drive, and insert your
own much smarter smarts. That's what I did routinely when I worked at
Maxtor writing hard drive test code. We needed to know how wide the
tracks really were, so we positioned the heads in ways that the PCB
smarts can't. The Head Disk Assembly (HDA) will support reading off
the center of the track, but the PCB won't. As you say, the drive is
designed to read only the most powerful magnetic domains (to describe
it rather simplisticly). But that limit is in the PCB, not the HDA.

Now, that was 20+ years ago, before perpendicular recording and some
other tricks for getting higher data densities. Whether any of that
applies to today's drives I don't know.


Charles Curley                  /"\    ASCII Ribbon Campaign
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