Destroying Data Beyond All Possible Recovery
How do you make a hard drive completely unreadable? A team at Ga Tech explored a broad range of possible destruction techniques, including burning diskettes with heat-generating thermite materials, crushing drives in presses, chemically destroying the media and finaly, exposing the disks to a magnetic force microscope.
If you ever need to get rid of a drive at home, the [GAS] team recommend using the good old "Sledgehammer" technique: Just wipe your disk using a utility like Darik's Boot and Nuke, then bring it outside and whack it with a sledgehammer until you cannot recognize it anymore. If the drive's platter is broken in multiple pieces, your data will probably remain permanently unrecoverable and no, freezing the disk won't help you in this case!
If you erase the data by whatever means, you should see a surface devoid of any specific pattern or periodicity,” Knotts explained. “Our goal was to see a random distribution of magnetization that would indicate a clean disk.