Information - Technology
Information - Technology
Data carrier degaussing
Degaussers are used for fast, safe and effective removal of information on magnetic data carriers such as hard disks and tapes. Below you will find additional information about the applications of degaussers.
What is degaussing?
The term "degaussing" is derived from Johann Carl Friedrich Gauss (1777-1855), a mathematician who researched electromagnetic fields. Degaussing
is basically the process of demagnetising; erasing the magnetic signal on data carriers such as hard disks and tapes.
All magnetic media have a magnetic property, called coercivity, which is measured in Oersted (Oe) units. The
Oersted (Oe) value indicates how simple or difficult a data carrier can be erased. Higher Oe media require a stronger magnetic field. Degaussers generate a
controlled magnetic discharge (pulse) or a continuous magnetic field that is measured in units of Gauss,
Tesla or Oersteds (Oe).
When magnetic data carriers are exposed to the powerful electromagnetic discharge of a degausser, the magnetic data on a tape or hard disk is erased. The polarity of the magnetic particles is rearranged and the previously recorded signal is
How do magnetic media work?
To understand how a degausser works, we must first understand how information is recorded on magnetic media (hard disks, tapes and cassettes).
Information on audio, video and data tapes is recorded by applying a magnetic signal to a tape. Magnetic tapes have three basic components: a fine iron oxide powder, a binder and the tape. A tape recorder contains both recording and playback
headers. These heads are small electromagnets. During recording, the recording heads create a magnetic field that changes the positioning of the fine iron oxide powder on the surface of the tape into a digital recording pattern. The playheads
read this pattern and convert it into sound, video or computer data.
Hard disk drives work in a similar way. Information is stored on round flat metal discs (platters) that contain a fine coating of iron oxide or chromium dioxide. Above the revolving platters a read/write head moves, similar to a turntable.
With small electric pulses from the head, the surface of the disc is magnetised. Data is recorded using binary code, a sequence of ones (1) and zeros (0).
Which types of degaussers are there?
There are three types of degaussers; "Pulse" degaussers, "coil" degaussers and "permanent magnet" degaussers.
• Pulse degaussers are specifically developed for erasing hard disks. The higher coercivity of hard disks with respect to tapes requires a more powerful magnetic field than can be generated with a coil degausser. Pulse degaussers generate a short,
very powerful electromagnetic discharge (Capacitive Discharge) to remove the magnetic signal on platters from a hard disk. A pulse degausser uses capacitors with a high capacity for storing an electric charge. Charging the capacitor takes between 10
and 70 seconds, depending on the model degausser. As soon as the capacitor is charged, the degausser can discharge it in a short, very powerful pulse. A hard disk is placed in the "degaussing chamber" of a degausser. The electromagnetic discharge is
sent through this chamber so that a hard disk is effectively erased.
• Coil degaussers are suitable for erasing tapes and cassettes. A coil degausser uses a magnetic coil to generate a powerful continuous magnetic field. This magnetic field is directed so that it is strongest at the top of the degausser. When
tapes are moved through the magnetic field, the recorded magnetic signal is erased.
• Permanent magnet degaussers use rare, natural magnets to produce a magnetic field. This degausser does not require electricity to function.
Which media can be wiped with a degausser?
All magnetic data carriers such as hard disk drives, tapes and cassettes can be erased with a degausser. Flash memory (USB sticks, memory cards, SSD's) is non-volatile memory based on the
EEPROM technique. Data carriers with flash memory do not use a magnetic signal and can not be erased with a degausser. Flash memory can be erased or destroyed.
"Pulse" degaussers have been developed for erasing hard disk drives. This new generation of degaussers does not work with a permanent magnetic field but with a short, very powerful electromagnetic discharge (Capacitive Discharge). This way the modern
large capacity hard drives can also be effectively erased. Pulse degaussers are available as manually operated systems for smaller numbers or as automatic systems for large numbers. Hard disks can not be reused after being erased in a degausser. Due to
the strong electromagnetic pulse, various internal components such as the read / write head are also permanently damaged. If hard disk drives have to be reused, they should be sanitized with an Eraser.
The "coil" degaussers are suitable for erasing audio, video and data tapes and floppy disks. These degaussers work with a strong electromagnet which develops a permanent magnetic field. Tapes are moved one or more times through the magnetic field to
completely erase all data. The disadvantage of coil degaussers is the limited cycle of use. The strong magnet coil develops a lot of heat, so that a coil degausser needs to be cooled regularly. The force of the magnetic field of most coil degaussers
is relatively limited so that these degaussers are not suitable for erasing hard disk drives.
Degauss or physically destroy?
Physical destruction of hard disk drives and other magnetic data carriers is often seen as an effective and safe method for data destruction. However, this is not the case. A hard disk drive can be crushed into pieces with a Shredder, bent with a
Crusher or pierced with a Puncher. Each of these methods ensures that a hard disk is damaged and can no longer be accessed. However, the magnetic signal on the platters is still present. Even when a platter of a hard disk drive is cut into very small
fragments, these fragments still contain information. Due to the high data density of modern hard disk drives, a fragment of 1x1 cm can still contain Gigabytes of information. With the help of the right knowledge and equipment, this information could
To ensure that a hard disk does not contain any information before it is physically destroyed, degaussers are used. The
NSA / CSS Storage Device Sanitization Manual describes three methods for safely destroying information on hard drives;
• Degaussing (erasing with a pulse degausser)
• Disintegration (shredding in particles of a nominal maximum of 2 millimeters long)
• Incineration (heating the coating of the hard disk platters to 2000 degrees)
A 2-step procedure is often used to destroy hard disk drives. First a hard disk drive is erased with a degausser. Because a hard drive erased with a degausser can not be determined to be erased, as a second step the hard drive is physically destroyed
with a shredder, crusher or puncher.
Degauss or sanatize?
If hard disk drives need to be reused, they can not be wiped with a degausser. The electromagnetic discharge of a degausser usually damages internal components of the hard disk drive. Existing information on a hard disk can in that case be
overwritten with an Eraser / Duplicator. This proces is refered to as sanitization.
A hard disk eraser can simultaneously erase multiple hard disks without software or PC connection. There are erasers available for SATA / IDE or SAS / SATA. An eraser offers various methods for erasing hard disks; "Quick Erase", "Full Erase",
"Secure Erase" and "DoD Erase".
The Secure Erase function uses the controller of the hard disk itself to erase the entire disk, including data sectors,
HPA (Host Protected Area) and any bad sectors.
De Secure Erase functie gebruikt de controller van de hard disk drive zelf om de volledige schijf te wissen, inclusief data sectoren,
HPA (Host Protected Area) en eventuele bad sectors.
The DoD Erase function supports the 5220.22-M (3-pass) and RCMP TSSIT OPS-II (7-pass) standards. These
mthods will overwrite a hard disk drive several times.
A major disadvantage of erasing hard disk drives with an eraser is the time required. A hard disk has to be completely overwritten one or more times. Depending on the speed and capacity of the hard disk, this process can take several hours.
Degauss White Paper
Language: EN - File: 0,1 MB
Examination of Data Erasure Tools and Methods
Language: EN - File: 21,0 MB
Magnetic Fields while using a degausser
Language: EN - File: 0,3 MB
NSA/CSS Storage Device Sanitization Manual
Language: EN - File: 0,2 MB
Data Reconstruction from a Hard Disk Drive using Magnetic Force Microscopy
Language: EN - File: 2,1 MB
Hard Drive Sanitization Process Risk Matrix
Language: EN - File: 1,0 MB
Data Elimination 101
Language: EN - File: 10,0 MB
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