Wednesday, March 1, 2006

How to destroy a hard drive (on purpose)


By David Gewirtz

Last summer, we moved the ZATZ offices from New Jersey to Florida. We've been enjoying a winter that's rarely gone below 60 degrees and so far, have avoided any serious hurricane scares. When you move, you discover all sorts of things that have been gathering dust in the corners, under boxes, and on shelves. As we packed, one of our most challenging discoveries was just how many old hard drives we had sitting around.

Over the years, rather than destroying or tossing the drives, we've kept them around as backups. But after carefully wrapping and packing each individual drive for shipment (and some drives were, get this, one gig drives), and then carefully unwrapping and unpacking each one here in Florida, I realized it was time to clear out some of these drives. But it wasn't until I was able to pick up a couple of 250GB SATA II drives for a whopping $99 each that it just became silly to have shelves and shelves of old hard drives sitting around.

My plan was simple: back up the old drives onto the new 250GB backup drive, securely wipe the data on each drive, and then destroy the drives' platters. These drives contained confidential information, source code, financial data, and so on, so we couldn't just toss the drives. They had to be securely destroyed. And so began a surprisingly fun project to clear them out.

Backing up was simple. I used a variety of tools to get the data moved over to the bigger drives. Where this project deserves documentation is in the wiping and destructions phases.

Securely wiping the drives

Although there are a relatively large number of commercial programs available to wipe a drive, one of the very best is free. DBAN (otherwise known as Darik's Boot and Nuke) is a bootable Linux CD-ROM that contains a killer wipe program. The program, shown in Figure A, supports a quick erase mode, Canadian RCMP TSSIT OPS-II standard wipe, American DoD 5220-22.M standard wipe, Gutmann wipe, and PRNG (Pseudo-Random Number Generator) stream wipe.


To get a screenshot, we're showing this on a virtual PC. (click for larger image)

The process is very simple. Make sure the drive you're wiping is on the IDE chain. Then boot the CD-ROM, select the wipe method you want (we generally use DoD, Department of Defense), and let the program run overnight.

Before you go ahead and do this, though, there are some relatively obvious cautions to consider. First, make sure you're wiping the right drive. It wouldn't do to wipe your backup drive after you've saved data to it. To prevent this, I unplugged the SATA drive prior to booting DBAN. Next up, double-check the drive's model number so that you're 100% sure you're specifying the right drive. And, finally, triple-check everything before you run the wipe.