One of the most secure ways to eliminate information on hard drives and magnetic computer tape media is to degausserase the information. Simply put, degaussing is a magnetic field using an alternating field of sufficient intensity to saturate the media. The magnetic field is then slowly withdrawn or reduced and the magnetic media is left in a magnetic neutral state, or erased. Part of the hard drive has a program called a servo, installed on the drive by the manufacturer, which also is erased. Degaussing the servo renders the drive useless.
A common misperception many first time degausser users have is their belief that they must have a degausser that is Department of Defense (DOD) or National Security Agency (NSA) compliant. Usually, when I question this statement, folks tell me their boss said that was a requirement. Or, they tell me it has to be Sarbanes- Oxley, FACTA, or HIPAA compliant. These regulations are guidelines and do not tell you what equipment to use or indicate a specific way of eliminating proprietary data. They simply state that you have to do it.
Another misperception concerns DOD approval. The DOD does not approve of anything, but merely recommends. If a manufacturer presents a degausser to DOD and the specifications claim it will erase a 300 GB hard drive, then DOD would probably add it to their list of recommended products. The problem is DOD, as of this writing, has not tested or recommended products in several years. This means that all the degaussers that degauss high coercivity drives and tape made today have never been tested by a governmental agency. This does not mean newer degaussers will not work. In fact, they function quite well. There are a few degaussers that are approved by DOD and NSA, however, they have limited erase capabilities (megabyte capacity) and were blessed several years ago.
CIO Research Library 
