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Posted May 3rd, 2011

What is a Degausser?

Customers are always asking us: what is a degausser and do we need to use hard drive degaussing service?

Well, first let’s start by explaining what a degausser is.  Basically, a degausser is a machine that changes the magnetic domain of magnetic data storage devices.  The magnetic domain is where the data is stored.   Examples of magnetic storage would be things like backup LTO and DLT tapes, VHS tapes, cassettes, reel-to-reel tapes and all types of hard drives. Compact Discs (CDs) are not considered magnetic storage because the data is stored on the disc with optics.   When the degausser is applied to magnetic domains the information is scrambled into random patterns.  This process renders the data that was stored in these magnetic domains unreadable.

Some generic magnetic storage devices can be reused after the degaussing process has taken place.  Reel-to-reel tape and VHS video cassettes and older media types are examples of these kinds of devices.  However these items are so old that saving them or reusing them is generally not a common practice because of the very limited storage capabilities.

For other forms of newer data storage like computers, laptops and server hard drives and some backup tapes, degaussing renders the media completely unusable because of permanent damage to the storage system.  This happens because of damage to the special servo control data that is written onto the media at the factory by the manufacturer.  Once the servo track is damaged, it can not be corrected.  Degaussing removes not only the stored data on the device but also removes the servo control data, and without the servo data the device is no longer able to determine where data is to be read from or written to on the magnetic media.

Here are a few terms and their definitions that you might hear if you are talking about a degausser:

Oersted – A unit of magnetic intensity equal to the intensity of a magnetic field in a vacuum.  How does that apply to a degausser? Oersted is a measurement applied to magnetic media. Most current tapes have an energy level rating of 1800 oersted or higher.  Hard drives can have an oersted rating up to 5000, which is the about the same as the most powerful degausser in the commercial market.

Coercivity – The amount of applied magnetic field (of opposite polarity) required to reduce magnetic induction to zero.  How does that apply to a degausser? This is the ease (or difficulty) by which magnetic media can be demagnetized. A tape with an oersted rating of 1800 might also be called a high coercivity tape.

The terms Oersted and Coercivity are often used interchangeably, which only makes things more confusing. Just remember that the newer the technology, the higher the oersteds needed to erase the item.

OK, now that you know all of the fun technical jargon regarding how a degausser works, let’s talk about why anyone would ever need to use one.  Most of the time, it is because of a federal law that needs to be followed.    This usually applies to clearance-level information like “Classified” or “Top Secret.”  In an attempt to protect the country’s classified information, several different federal agencies have standards and procedures that have been written on how to handle the destruction of sensitive data.  Those standards involve the use of a degausser and then physical destruction of the unit.

OK, so why?  Well, some people do not understand that destruction of the storage device alone technically does not remove the data. It just makes the device (tape or hard drive) unusable.

This means that even though the item has passed through a shredder, it still has data on the little pieces that can be recovered.  Many of our competitors claim that after shredding the data is not recoverable.  This is a possibility, albeit unlikely, depending on where the shredded hard drive was sent.  After shredding a hard drive, most computer experts would not be able to retrieve data from the shredded pieces.  However, there are some people/places/countries that would indeed be able to retrieve the information.  How is this possible? If you take a magnet and smash it on the ground, the magnet will break into small pieces, but each of these pieces is still magnetic. Hard drives work the same way. Because the hard drives or tapes store the data using magnetics, even a small piece of the device retains its magnetic properties, and therefore can still be read.

Most companies do not need to use hard drive degaussing for their data destruction needs.  This is because shredding provides enough destruction for the type of information stored on the device.  Another factor that influences the degaussing decision is that this service doubles the cost of the destruction process.  However, if the data on the storage device is classified, there is no option and degaussing must be used before the device is shredded.

Securis utilizes one of the fastest degaussers available to destroy magnetic storage devices.  We can provide hard drive degaussing service on-site at your office or off-site at one of our facilities. To learn more about our degausser, click here.

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