[unisog] Wiping hard drives before computer transfer

Paul Heinlein heinlein at cse.ogi.edu
Fri Jan 24 16:54:59 GMT 2003


> It is free and can clean a 120G 7200rpm in 27-30 hours for a 35 pass
> overwrite (call me Mister Clean ;-) ) using a 1.7 GHz P4.

Peter Gutmann, the apparent originator of the 35-pass overwrite
technique, has written a good academic treatment of the subject:

  http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

He makes the point that you really ought to know the type of encoding 
used on the drive before trying to scrub it:

    If you're using a drive which uses encoding technology X, you only 
    need to perform the passes specific to X, and you never need to 
    perform all 35 passes. For any modern PRML/EPRML drive, a few 
    passes of random scrubbing is the best you can do.

Just trying to complicate things,

--Paul Heinlein <heinlein at cse.ogi.edu>



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