Data erasers for hard disks
Hard disk extinguishers (also referred to as degausser in the jargon) are devices in which magnetic-based media are exposed to a strong magnetic field (alternating field, DC field or pulsed field). With the use of these extinguishing systems for hard drives then the deletion is made.
If a sufficiently strong magnetic field is present, all magnetic recordings that are present on the data carriers are destroyed by means of the hard disk wipers by the demagnetization process. As a result, a reconstruction of the data stored on the data carriers is no longer possible. Thus one can destroy the contents of data carriers by these extinguishing devices for hard disks.
In order to ensure that these hard disk wipers are completely erased, it is necessary that the extinguisher's magnetic field be significantly larger (about twice) than the coercive field of the disk to be erased. Only then the use of the extinguishing systems for hard drives is successful and the deletion can be carried out in the form of extinguishing systems for hard disks.
Hard disk extinguishers - the modern form
The extinction loss of 90 dB listed in the standard DIN 33858 (dealing with the erasure of magnetic data carriers), in which only the noise floor of the data carrier could be included in the measurement after the data carriers were treated with a data erase unit, is up to date technically obsolete when using the data erase unit. Therefore, when using the disk-erasing devices, another method for the data-erasing unit must be used. Otherwise you can not perform the deletion with the use of the deletion devices for hard drives as a data erase unit.
In the modern data carriers that are today treated with such a data erase unit, the signal-to-noise ratio is much smaller than 90 dB. Therefore, it makes sense to perform a complete erase when using the extinguishing systems for hard drives, because due to the aforementioned facts when using a data erase unit no signal is verifiable over the noise floor. Therefore, the measuring method used hitherto when using extinguishing systems for hard disks is no longer applicable.
Furthermore, when deleting magnetic data carriers when using the extinguishing systems for hard drives to note that contain the extinguishing systems for hard disks to be deleted a corresponding information for the guidance of a read / write head. This header can then no longer be used after deletion by a data deleting unit, because the use of the data deleting unit has also deleted the servo track.