For those who think 1 pass is enough

[Super Fast]

I assume this applies to even CCleaned drives, but google this & see what you think...

 

The recovery of at least one or two layers of overwritten data isn't too hard to perform by reading the signal from the analog head electronics with a high-quality digital sampling oscilloscope, downloading the sampled waveform to a PC, and analysing it in software to recover the previously recorded signal. What the software does is generate an 'ideal' read signal and subtract it from what was actually read, leaving as the difference the remnant of the previous signal.

- Dr Peter Gutmann PhD, University of Auckland

 

So, yeah, more than 1 pass needed?

 

If you want it securely gone!

[Guest]

But for the typical user 1 pass is enough. If you want your data gone blow up your hard drive.

 

Doesn't Gutmann imply you need physical access to the hard drive ("... with a high-quality digital sampling oscilliscope, ..."). In which case you could do bit by bit analysis which can recover data from even damaged platters of hard drives.

[Augeas]

This has been done to death in these forums, so it's worth having a search.

 

Gutmann published in 1996, after working on Winchester disk technology. Even I have moved on from then. Gutmann's paper cited no examples where data had been recovered after being overwritten. We're still waiting. For any disk produced in the last 15 years Gutmann is an irrelevance. (That's a posh word for blooming nuisance.)

[Super Fast]

Oh, I am just wondering, I am not really as interested in Gutmann.

 

What I am really interested in, is if 1 time can be recovered, how safe is 3 passes?

 

Should be pretty hard to recover, right?

[Augeas]

Well, your quote was from his 1996 paper, and the premise in 1996 that one pass can be recovered remains unproven. So three passes would be pretty hard to recover, but the evidence is that one pass is impossible.