MDCR wrote:
Gutmans proposed wipe claimed that it took 7x5=35 passes to wipe a drive clean (which i never read any explanation or research for).
See his paper 'Secure Deletion of Data from Magnetic and Solid-State Memory', which can be found on the net, and particularly section 3. (http://www . cs . auckland . ac . nz/~pgut001/pubs/secure_del.html)
That paper makes it clear it's not 7x5 -- it's 22 patterns designed for various combinations of MFM/RLL, and additional passes for other forms of encoding.
And the added 'Epilogues' seem to make it quite clear that those 35 passes were for the case where you did not know the encoding method used. If you you knew for certain the disk was a EPRML disk, a few passes (pass 1-4) with random data would be enough. It would be superfluous to use patterns intended for different types of MFM/RLL encoding.
As for the OP, I think the Epilogues in the cited work answer your question.
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