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I was reading somewhere that secure HDD erasing programs erase all disk sectors multiple times with a random sequence of bytes.
My question is: logic tells me that surely doing it once to every single sector (including those marked bad by the HDD) is enough?
If it weren't enough then we should be concerned about the ability of the HDD to reliably write/retrieve data in the first place.
To me it sounds like some bureaucrat without any real knowledge deciding that it would be a good idea.
Am I missing something?
EDIT: I'd like to add the following link that seems to support my argument. http://hostjury.com/blog/view/195/the-great-zero-challenge-remains-unaccepted
1So what you're saying is that it's very unlikely you'd recover anything useful. I think your last statement sums it up. "some people do have this requirement, or at least think they do". – Matt H – 2011-09-14T08:59:20.817
The problem is the imperfection of disk tracking. If an overwrite pass is slightly to the left of slightly to the right of the write pass it's overwriting, there's a fear that it may be possible to recover the original data by using a narrower reading head and aiming it off the center of the track area. However, there's no evidence this is actually possible on modern hard drives. – David Schwartz – 2012-03-10T07:25:38.770