Degausser vs. Eraser: Which Is Right For You?

Many of our customers ask us about the difference between degaussers and erasers, and which is best for their specific needs. More often than not, the answer lies in whether the customer would like to reuse or simply dispose of the media.

As a general rule, if you wish to eliminate all information from your media and dispose of it, the best method is using a degausser of proper strength.

An alternating current (AC) bulk degausser will completely erase data and all other signals recorded on magnetic media. Degaussing is a process where magnetic media is exposed to a powerful, alternating magnetic field of sufficient intensity to completely saturate the media. Degaussing removes all previously written data, leaving the media in a magnetically blank state.

Certain types of tape do not have manufacturer-recorded servo tracks – including DLT, SDLT, 3480, 3490, 3490e, Digital Video – and these tapes can easily and safely be degaussed and then reused.

However, if you wish to reuse your media and it has factory prerecorded magnetic servo patterns, an eraser is the only solution.

Several types of magnetic data cartridges and hard drives have manufacturer-recorded servo tracks, and if these servo tracks are erased, the tape or drive loses its ability to be read and thus cannot be reused. Some examples of media with servo tracks are computer hard drives, LTO, Travan (ADR, SLR), AIT, Magstar 3590, and StorageTek 9840 and 9940.

A cartridge or hard drive eraser will permit you to completely erase the data from the media and still reuse it, thus potentially saving your company thousands of dollars.

The process of erasing tape media entails deleting specific amounts and fields of stored data so that the data is rendered completely unreadable. However, the erasing process leaves the manufacturer-recorded information on the tape completely unaltered. This process is accomplished by modifying tape drives. An erase head is inserted into the tape path, which has erase gaps at the servo tracks. The erase head will then erase everything on the tape, except the servo tracks. The tape cartridge can then be reused.

A different process is used to erase hard disk drives. The drive eraser simply writes over every data location on the disk one time, so sector and servo information remains on the disk. The Department of Defense has rigorous requirements for security erasure, and the disk is overwritten eight times so no electronic pulse of any kind remains on the disk. This procedure has DoD and NSA approval.

Data Devices International, Inc. offers a complete line of both degaussing and erasing equipment. Visit our Web store at for more specific information on products that can help you secure your magnetic media. If you have questions about how best to handle your media, please contact us and we will be happy to help you.

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