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detritus, excessive shock or vibration (such as accidentally dropping a running drive), can cause a head to bounce against its disk, destroying the thin magnetic coating on the area the heads come in contact with, and often damaging the heads in the process. After this initial crash, countless numbers of fine particles from the damaged area can land on other areas and can cause more head crashes when the heads move over those particles, quickly causing significant damage and
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Older drives typically rotated far more slowly and had larger heads flying higher above the surface of the medium. However, since in many cases, the medium was housed in a removable cartridge or pack and since air filtration was comparatively crude, crashes were fairly frequent and invariably
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is made using thin film techniques that include materials hard enough to scratch through the protective layers. A head crash can be initiated by a force that puts enough pressure on the platters from the heads to scratch through to the magnetic storage layer. A tiny particle of dirt or other
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Head crashes have been a frequent problem on laptop computers since they first incorporated hard drives, since a laptop computer is more liable to be dropped or jostled than a stationary machine. This has led to the development of
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that "park" the head at a safe distance from the disk when sudden motion, such as that of a dropped computer, is detected. Active Hard Disk
Protection software and sensors began appearing in laptops in 2003 with
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carbon. These two layers protect the magnetic layer (data storage area) from most accidental touches of the read-write head.
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in the mid-1990s used a thin liquid layer instead). The distance between the head and platter is called the
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This article is about hard drive failure. For the German-American band under the same name, see
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to offer protection against head crashes caused by accidentally dropping the drive.
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A head crash in a modern drive. Note circular scratch mark on the platter.
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line of laptops, becoming common around 2009 with the introduction of
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entrapped at the surface of its platter (some drives manufactured by
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352:"IBM ThinkVantage Technologies: Hard Drive Active Protection System"
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376:"HP Notebook PCs - Use ProtectSmart to Prevent Hard Drive Damage"
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Since most modern drives spin at rates between 5,400 and 15,000
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Read-write head of a hard disk making contact with the platter
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60:. Unsourced material may be challenged and removed.
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188:. The topmost layer of the platter is made of a
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331:Handbook of nanoscale optics and electronics,
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164:drive makes contact with its rotating
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