Clean hard drives without destruction

June 2010

There is a thriving industry for the destruction of computer hard drives in order to assure a worried client that no one will ever be able to read the confidential information off that drive.

In the minds of such people, resource wastage is a small price to pay for their peace of mind. And maybe that is the the way it should be. Maybe not.

Is there a better way to destroy data on a magnetic drive that doesn’t involve shredding the entire drive, which is what is normally done today?

Here’s a suggestion that starts, as usual, with redesign of the drive. The common method for completely removing magnetic information is degaussing, or demagnetizing. This shakes up all the bits and magnetic domains until they take up random positions, containing no information. Then the disk can be formatted from scratch and used. Physically, or mechanically, this operation causes no harm or destruction.

What if the bulk demagnetizer were built into the drive from the start, but simply sat there, doing nothing? It could be positioned exactly where it needs to be to exert its magnetic effect on the spinning disks. As a safety precaution, the demagnetizer could be made in such a way that there would exist no possibility at all of its suddenly going off and destroying data when that wasn’t wanted. For example, it could have no power source, until the drive was physically removed from its computer and an external power cord was attached to the demagnetizing unit.

If the degausser is expensive, not every drive needs to have this capability. Special drives for sensitive data can be sold at a premium. The drive manufacturers might find this feature quite attractive.

In a world where waste is considered just dandy (as long as the tiny, unimportant shards of steel are recycled) shredding seems unremarkable. But in a world to come, where waste is built OUT of every product, data destruction can be a more intelligent process.

January 2016

The cleaning of hard drives has made some progress since I wrote the above words. See this website for a review:
ZDNET article on data destruction

Recently solid state drives have made an appearance so it is no longer possible to be sure that your data is distributed in a known pattern on a physical disk.  Magnetic demagnetization will no longer work for these drives. The article details a special data destruction command called Secure Erase which finally and completely removes data from any storage. However, they point out that the feature is often disabled because manufacturers are afraid that users may invoke  it without realizing that all of their data will be gone forever.  Perhaps it can be enabled in the BIOS in that case.

The article also discusses methods of multiple encryption to remove data.

Don’t forget that the point is to be able to reuse physical drives without resorting to physical destruction.