Written By Sunil Chandna
Updated on Jun 16, 2022
Min Reading 3 Min
Data destruction is a growing industrial need gaining urgency with the rise of data protection laws that obligate organizations to destroy data in accordance with stringent regulations. "Permanent data destruction" is a prerequisite or qualifying parameter for any "compliant" media sanitization technique. Degaussing is one such data destruction technique based on demagnetizing the magnetic storage media such as hard disk drives and tapes.
This article presents an in-depth insight into "what is degaussing," how it works, types of degaussers, type of media degaussing supports, etc. It also helps understand viable alternative to degaussing and why organizations should avoid degaussing or limit its use in their data destruction strategy.
Degaussing is a data destruction technique based on demagnetizing or neutralizing the magnetic field used for data storage in magnetic media such as hard disk drives, floppies, etc.
You can visualize the magnetic storage media as a large "magnetized surface" split into several tiny sub-micron magnetic regions using a strong local magnetic field generated using a media writing head. These magnetized domains have their own local and uniform field orientations used for storing the data. The degaussing process eliminates these local magnetic domains by neutralizing their field orientations, thereby destroying the data.
Degaussing is performed using a degausser machine that applies a strong magnetic field to rearrange or randomize the existing polarity (orientation) of the magnetized domains on the storage media. As a result, the data recorded on these magnetized domains is principally destroyed. However, the efficacy of a degausser depends upon its magnetic field strength vis-à-vis the media it is degaussing.
Typically, the degausser must have 2–3 times the Coercivity of the magnetic media to degauss it effectively. Coercivity is the magnetic material's resistance to alterations in its magnetic field orientation and is measured in a unit called oersted. This fact means media with higher coercivity will require more powerful degaussing equipment and, therefore, will be challenging to degauss. As per NIST SP 800-88 guidelines, the emergent magnetic media with advanced recording technologies have higher coercivities. As a result, existing degaussers may not have adequate strength to sanitize them.
Further, precise matching of the degausser's strength vis-à-vis the media coercivity is crucial for effective degaussing. Meeting these prerequisites can pose a technical difficulty. As per NIST SP 800-88 Guidelines, "degaussing renders a legacy magnetic device purged when the strength of the degausser is carefully matched to the media coercivity. Coercivity may be difficult to determine based only on information provided on the label."
There are essentially three types of degaussers or degaussing devices based on the mechanism they use to generate the magnetic field, as follows:
Image: Coil Degausser
Image: NSA Listed Degaussers
Comparison of Degaussers
The following table compares the different degaussers against specific parameters, as follows:
Comparison Parameter |
Coil |
Pulse |
Permanent Magnet Degausser |
Operation |
Manual - Media is manually turned over several times to expose the surfaces. |
Semi-automated - |
Manual or automated – depends upon how the media is passed between the permanent magnets. |
Process Efficiency |
Low – needs multiple manual rounds. Typically, degausses a single media at a time. |
Moderate – depends upon the degausser design. The process can be done faster with conveyor belt design. |
Moderate – based on the capacity to degauss multiple drives and operation mode. |
Effectiveness |
Low to Moderate – depending upon the storage media capacity and coercivity. |
Moderate to high – based upon the pulse strength vis-à-vis the media capacity and coercivity. |
Generally high with NSA certified degausser. |
Heat Generation and Durability |
High - prolonged operation can reduce the degausser life. |
High - more durable than coil degausser as the heat is generated in short pulses. |
No heat generation as there is no involvement of electrical charge |
Health hazard |
Severe – |
Moderate – |
No risk to health, but it can affect the magnetic storage devices in close vicinity if there is a leakage. |
Size & Portability |
Small with easy movability. |
Lightweight and easy to transport. |
Large-sized, fixed setup with no portability. |
Media Reusability |
Renders the media unusable |
The degaussed media cannot be reused. |
Renders the media unusable |
Environmental Impact |
High – |
High – |
High – |
What Type of Storage Media Can be Degaussed?
The degaussing technique can sanitize the following types of magnetic storage media:
Disadvantages and Limitations of Degaussing
There are specific shortcomings of degaussing, crucial for consideration while defining an organization's data destruction strategy, as follows:
Data erasure or data wiping is a modern media sanitization technique based on overwriting the user addressable and hidden memory locations on a storage drive with binary patterns like 0s and 1s. The erasure technique destroys the data and renders it unrecoverable using multiple overwriting passes following specialized data wiping algorithms. Further, it verifies the overwriting passes to confirm the wiping efficacy against the desired outcomes.
Some of the inherent benefits and advantages of data erasure over degaussing include—
Suggested Reading: Data Erasure Vs. Degaussing
Read this article to get an in-depth comparison of data erasure and degaussing and why data erasure is better than degaussing.
Degaussing is an established media sanitization technique but it turns out outdated and less effective for the evolving magnetic storage media with higher coercivity. Further, it does not destroy the data stored on flash storage media. Newer techniques like data erasure provide a more effective, expansive, and scalable alternative for media sanitization in the current context. It equips organizations with a broader capability to wipe storage media with assurance.
BitRaser is NIST Certified
Related Articles
![]() |
NIST Clear |
![]() |
NIST-ATA Purge |
![]() |
US Department of Defense, DoD 5220.22-M (3 passes) |
![]() |
US Department of Defense, DoD 5200.22-M (ECE) (7 passes) |
![]() |
US Department of Defense, DoD 5200.28-STD (7 passes) |
![]() |
Russian Standard – GOST-R-50739-95 (2 passes) |
![]() |
B.Schneier’s algorithm (7 passes) |
![]() |
German Standard VSITR (7 passes) |
![]() |
Peter Gutmann (35 passes) |
![]() |
US Army AR 380-19 (3 passes) |
![]() |
North Atlantic Treaty Organization-NATO Standard (7 passes) |
![]() |
US Air Force AFSSI 5020 (3 passes) |
![]() |
Pfitzner algorithm (33 passes) |
![]() |
Canadian RCMP TSSIT OPS-II (4 passes) |
![]() |
British HMG IS5 (3 passes) |
![]() |
Zeroes |
![]() |
Pseudo-random |
![]() |
Pseudo-random & Zeroes (2 passes) |
![]() |
Random Random Zero (6 passes) |
![]() |
British HMG IS5 Baseline standard |
![]() |
NAVSO P-5239-26 (3 passes) |
![]() |
NCSG-TG-025 (3 passes) |
![]() |
5 Customized Algorithms & more |
Listening...