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The Challenge of Data Destruction

Two weeks ago in my editorial "Wipe Old Hard Disks Clean--Reprise," I wrote about erasing disk data and mentioned some software and hardware tools that can help with that task. This week I want to follow up with some more information.

Sande Nissen wrote to tell me about the difficulties faced by the college he works for. Each year, the college replaces a portion of its computers, and this year he will need to dispose of about 200 computers. Before those systems can be sent to a recycler, the data on the disks must be destroyed. According to Nissen, the college's tool of choice at the moment (Symantec Ghost Solution Suite's GDisk component) requires about 1.5 hours per gigabyte to wipe disk data when using a Department of Defense-certified erasing routine. With so many disk drives and so many gigabytes to erase, the college needs a faster way to ensure data destruction.

Nissen said the college doesn't trust demagnetizers (degaussers), which erase disk data by subjecting the drives to a strong magnetic field. Degaussers are also expensive, costing anywhere from a few thousand dollars to more than $25,000. Even renting the equipment is expensive. Some companies charge $1400 per month per rental unit. If you're interested in degaussers, here are some links to manufacturers and rental companies:

An important thing to know about degaussers is that there are two basic types: open field and closed field. Open field units expose their magnetic fields to the surrounding environment, which means you and anything else that might be within range. That might pose health risks and could damage anything magnetic in the vicinity, including the magnetic strips on your credit cards. Closed field units, which are far more expensive than open field units, typically let you insert the drives inside the unit and contain the magnetic field emissions.

Nissen said the college has tried physically destroying the drives by driving a nail through them or smashing them. A few years ago, I read about people using liquid hydrogen to help destroy disk drives. Liquid hydrogen quickly freezes and makes brittle whatever it comes into contact with. If you dip a drive into it, you can then easily smash the drive with a hammer. This approach is a bit extreme because liquid hydrogen is very dangerous.

If you have only a few drives to erase, destruction is relatively simple. But as we've learned from Nissen's situation, the task becomes much more of a challenge when you have a lot of drives. Do you know of a better way to destroy data on a large number of drives, with a high degree of certainty that no one can recover the data? If so, send me an email message with the details.


Don't miss today's Web chat with Randy Franklin Smith on the topic "The Security Event Log: The Unofficial Guide." It's at 12:00 P.M. Eastern (9:00 A.M. Pacific). For more information, go to

TAGS: Security
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