Greg London wrote: > ...it would seem to me that the right bit of hardware hooked directly > to [the drive head] would be the best way to wipe a drive. If you > drive random data onto the data wire and slowly work the head from > the inside to the outside track, you would wipe out formatting data, > hidden sectors, sectors marked as bad, etc.
True, but your custom control board would need to also control the head position servos, and know substantial low-level details about the drive, like the head design and the step size of the positioning servos. > The one example where this actually is important, > is if you're returning a drive under warranty. > You want to wipe the data, but you can't take > the drive apart and still get you're money back. If you do the above, they'll notice that you trashed the synchronization tracks on the drive. To avoid that, your custom controller would have to be even more sophisticated, and read the proprietary encoded sync tracks and use them to precisely position the head. Presumably drive manufacturers are competing fiercely to push the envelope on drive capacity, and thus encoding schemes and head technologies are proprietary and constantly evolving. Making the development of a custom controller board impractical for mass production. At least that used to be the case. With the industry consolidation, the designs may be more stagnant these days, though it seems they're keeping up with Kryder's Law[1][2] (like Moore's law). 1. https://en.wikipedia.org/wiki/Mark_Kryder#Kryder.27s_Law 2. https://en.wikipedia.org/wiki/Talk:Mark_Kryder#Numbers_for_Kryder.27s_Law_are_wrong If you are going to go to all this trouble, it might be easier to reverse engineer the diagnostic ports (JTAG) and diagnostic modes (enabled through jumpers) to attain lower-level access to the drive, while still gaining some abstraction from the head and track design by leveraging the on-board electronics and firmware. I'd speculate that companies like Seagate keep the APIs for these diagnostic modes fairly static so they can avoid creating new test fixtures for each new drive model. No doubt this is all stuff the better data recovery services have figured out. -Tom -- Tom Metro Venture Logic, Newton, MA, USA "Enterprise solutions through open source." Professional Profile: http://tmetro.venturelogic.com/ _______________________________________________ Boston-pm mailing list [email protected] http://mail.pm.org/mailman/listinfo/boston-pm
