full-disclosure - erase with magnet

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From: fulldisc at ultratux.org (Maarten)
Subject: erase with magnet

On Saturday 03 April 2004 17:36, B$H wrote:
> Hi all!
>
> I'm interested in the original question about erasing a harddrive using a
> magnet. Is it possible to erase data on a hard disk drive with a powerful
> magnet, but then be able to use the drive and the PC again?

No, not really.  

The thing is, there is already a _very_ strong magnet inside the drive, in the 
head actuator assembly.  In order to wipe the magnetic field on the platters 
you need to get a magnet _much_ closer to the platters' surface than a few 
centimeters, nearly as close as the read/write heads are.  As a magnetic 
field gets exponentially weaker as the distance increases, you would need 
such a strong magnet that you would kill the drive, or even yourself or your 
surroundings.
It is very doubtful such a magnet even exists in a 'normal' form (i.e. not 
standing in the middle of a 'particle-accelerator' (not sure if that is the 
correct term).  But a project like a railgun might provide a magnetic field 
that could qualify. Or the shrinking-coin machine, certainly [*]

[*] I don't have the URLs handy, but slashdot linked to those projects. 

You could open up the drive to erase it, but then that would wreak havoc on 
your "able to use the drive again" requirement...

-- 
Linux: Because rebooting is for adding hardware.