On 9/29/12, Jude DaShiell <jdash...@shellworld.net> wrote: > run d-ban on the disk and do a thorough cleaning of the disk then try ~ The only "data erasure" I know of is shredding your hard drives to pieces, smashing them to dust and melting them. This is by the way what US gov does with their hard drives and monitors ~ lbrtchx ~ http://en.wikipedia.org/wiki/Hysteresis ~ http://en.wikipedia.org/wiki/Data_remanence ~ http://en.wikipedia.org/wiki/Coercivity ~ http://en.wikipedia.org/wiki/Degaussing For certain forms of computer data storage, however, such as modern hard drives and some tape backup drives, degaussing renders the magnetic media completely unusable and damages the storage system. This is due to the devices having an infinitely variable read/write head positioning mechanism which relies on special servo control data (e.g. Gray Code) that is meant to be permanently embedded into the magnetic media. This servo data is written onto the media a single time at the factory using special-purpose servo writing hardware. The servo patterns are normally never overwritten by the device for any reason and are used to precisely position the read/write heads over data tracks on the media, to compensate for sudden jarring device movements, thermal expansion, or changes in orientation. Degaussing indiscriminately removes not only the stored data but also the servo control data, and without the servo data the device is no longer able to determine where data is to be read or written on the magnetic medium. The medium must be low-level formatted to become usable again; with modern hard drives, this is generally not possible without manufacturer-specific and often model-specific service equipment. ~
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