What Is Degaussing?
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.
How Is Degaussing Performed?
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."
Types of Degaussers
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
- Coil Degausser:
The coil degausser comprises a copper wire wound on a steel core. The setup produces a strong electromagnetic field when activated using alternating current. This electromagnetic field is used to demagnetize hard drives and other types of magnetic storage media.
- Capacitive Discharge Degausser:
This degaussing device stores electrical charge in a capacitor, discharging the energy as a strong high-frequency electromagnetic pulse to demagnetize the storage media. This process degausses the magnetic storage media, thereby destroying the data. The capacitive discharge degausser is also known as the pulse degausser.
- Permanent Magnet Degausser:
These are natural rare-earth magnets such as neodymium magnets with extremely high field strengths. The permanent magnet is arranged in a specialized structure to degauss magnetic media such as hard drives, tapes, etc. Unlike coil or pulse degaussers, the permanent magnet degausser does not require an electrical charge.
Image: NSA Listed Degaussers
Type of Storage Media That Can be Degaussed
The degaussing technique can sanitize the following types of magnetic storage media:
- Hard Disk Drives: 2.5 and 3.5-inch hard disk drives
- Tape Drives: Linear Tape-Open (LTO), Digital Linear Tape (DLT), Advanced Intelligent Tape (AIT), Quarter Inch Cartridge (QIC), etc.
- Floppy Disks: 8-inch, 5 1⁄4-inch, 3 1⁄2-inch floppy disks
Advantages of Degaussing
- Complete Data Erasure from Magnetic Drives, Floppies, Cassettes, and Tapes. Many organizations consider it a foolproof solution to get rid of data.
- Degaussing is considered a fast process, especially when a large amount of drives are to be decommissioned.
- Degaussers are easy to use, and even non-technical staff can use the degausser.
Limitation of Degaussing
There are specific shortcomings of degaussing, crucial for consideration while defining an organization's data destruction strategy, as follows:
- Low Efficacy of Data Destruction
As understood earlier, degaussers need to have sufficient magnetic force, carefully matched with the media coercivity, to attain successful degaussing. Also, their efficacy is based on the equipment type, i.e., electromagnetic or permanent magnet degaussers, and their appropriate usage. To quote the NIST SP 800-88 Guideline – "assurance provided by degaussing depends on selecting an effective degausser, applying it appropriately, and periodically spot-checking the results to ensure it is working as expected." This functional issue with degaussing could hamper the data destruction strategy that spans a diverse variety of magnetic storage media with high coercivity.
- Limited Scope of Media Sanitization
Degaussers can sanitize only magnetic storage media and have no effect on flash memory-based storage, such as solid-state drives, USB flash drives, memory cards, etc. So, the technique is rendered useless if you need to sanitize flash storage media. The NIST SP 800-88 Guideline advises against relying on degaussing as the sole technique to sanitize flash storage devices or magnetic storage devices that also comprise non-volatile, non-magnetic storage. The Guideline categorically states, "Degaussing must not be performed as a sanitization technique on flash memory-based storage devices."
- No Scalability
Typically, degaussers are designed to sanitize a single hard drive to a few units together, allowing no scalability. For organizations that need to sanitize more than 8-10 drives at a time, degaussing is an inefficient technique with a slow turnaround and considerable manual effort and time consumption.
- Renders the Media Unusable and Generates E-waste
Degaussing turns magnetic storage media like hard disk drives, including IDE, EIDE, ATA, and SCSI drives, useless, with no residual value left to allow asset reuse or resell. This fact means degaussing is probably suitable only for "end-of-life" media with bad sectors. Moreover, Degaussing results in e-waste with associated implications for the custodian organization. The E-Waste needs to be handled properly, and compliance needs to be maintained with Environmental laws prevailing in the state.
- High Operational Costs
Degaussers, particularly the permanent magnet variant, are innately expensive due to their physical construct and use of rare earth metals. For example, NSA-evaluated degaussers with high oersted values can cost upwards of US$40000, incurring a significant operational expense. This cost can further add up for organizations with media sanitization needs spread across multiple facilities or branches.
Secure Data Erasure — An Alternative to Degaussing
Data erasure or data wiping is a 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. The main advantage of this method is that it can be done quickly and easily. Data Erasure is a secure data destruction method that leaves the device reusable and promotes a circular economy. Further, using software-based erasure, organizations can not only comply with laws and regulations but also meet their ESG goals.
Some of the inherent benefits and advantages of secure data erasure as an alternative to degaussing are listed below:
- Wider Scope of Media Sanitization
The software-based data erasure technique can sanitize a wider variety of storage media, including magnetic storage like hard disk drives and flash storage such as SSDs, USB flash drives, memory chips, phones, etc. Degaussing is ineffective for SSDs. You may read our article - Does Degaussing Work on SSDs to know more. Organizations can perform data wiping on laptops, PCs, Macs, Servers, and Chromebooks using a data erasure software like BitRaser that generates proof of data destruction and verifies wiping too.
- Higher Degree of Effectiveness
Data erasure is not concerned with aspects like magnetic storage media's field strength (coercivity) or the need to precisely match the coercivity value for effective media sanitization. It is primarily a software-based technique that can wipe any storage media within its scope by implementing one or other data-wiping standards (typically in the form of an algorithm). For example, professional data erasure software like BitRaser Drive Eraser can wipe hard drives, SSDs, and other storage media using 24 international standards such as NIST 800-88 Clear, NIST Purge, and US-DoD 5220.22-M. By implementing an established standard, data erasure can guarantee media sanitization with systematic assurance in the form of audit trails.
- High Scalability and Manageability
Professional data erasure software can erase thousands of storage drives simultaneously. In contrast with degaussing, which allows limited parallel media sanitization capacity, data erasure software allows extensive scalability to meet the needs across the usage spectrum. For example, professional data erasure software like BitRaser Drive Eraser can erase up to 65000 drives and devices together in a single workflow using the Network cloud variant. Further, with built-in provisions like a centralized cloud console, the tool allows data wiping across multiple Internet-enabled facilities with easy manageability. See the BitRaser Drive Eraser Variants comparison.
- Data Erasure Allows Media Reuse and Generate Zero E-waste
The erased storage drive can be reused immediately with no impact on its residual value. Data erasure prepares a thoroughly sanitized storage hardware asset, ready for reallocation, exchange, return, donation, refurbishment, resell, etc. Also, there is no e-waste generation as the erased media is re-assimilated for active usage unless it is an end-of-life or legacy asset that needs recycling. Data erasure is environmentally sustainable, unlike degaussing, and plays a crucial role in promoting a circular economy.
- Ease of Deployment: Data Erasure can be pre-customized and applied seamlessly across boundaries; it can be downloaded from any location, whereas a degausser has to be physically present to perform degaussing. What's more, with the prevalence of remote work environments post-COVID-19, degaussers cannot be sent to remote employee locations to destroy data in case of mass layoffs or contract termination. Remote Data Wiping Software is the wise solution in the case of remote work environments and comes as a cost-effective solution.
- Economical: Data erasure is a less expensive solution than degaussing, making it more affordable for businesses. The total cost of operation is very low in the case of data erasure compared to Degaussing.
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.
Ending Notes
Degaussing is an established media sanitization technique, but it is outdated and less effective for evolving storage media with higher coercivity. Further, it does not destroy the data stored on flash storage media such as SSDs, NVMe, M.2 drives, and Hybrid drives which are very commonly used media. Software-based techniques like data erasure that follow the overwriting technique provide a more effective, expansive, and scalable alternative for degaussing in the current context. It equips organizations with a broader capability to wipe storage media with assurance. Standards like NIST 800-88 and IEEE 2833-2022 promote media sanitization using a software-based data erasure method that erases data permanently and renders the device usable for future reuse.
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