Head crash

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The head crash is the direct contact of the surface of a magnetic disk ( English Platter ) of a hard disk by the read / write head, resulting in mechanical damage to the storage layer and the contamination Platter performs abraded surface material. There is a risk of destruction and loss of data.

Open hard drive after a head crash. The rubbing marks left by the damaged read / write head on the magnetic disk are clearly visible.
Disk surface covered with abrasion from the magnet surface


In extreme cases, in the event of a head crash, the read / write head can stick to the platter surface shortly after it has been placed on the surface and then be torn off by the rotation of the platter.

After a head crash, the hard disk is usually no longer bootable or only runs for a short time until it finally fails. In most cases this is caused by abraded material, which is deposited as a thin film on the platter and thus additionally damages the heads and the surface of the platter. Sometimes the heads are mechanically fixed / jammed when the disk is switched off due to abrasion on the disk surface, so that under certain circumstances the static friction is so great that they tear off when the disk is started again or prevent the disk from starting.

Further damage to the data-carrying surface can occur because the heads are positioned in other, previously unaffected areas during read / write operations and there come into conflict with the abraded particles. After a head crash, the data on a hard drive can often only be recovered by data recovery companies with special equipment.


Normally, due to the ground effect, there is a thin air cushion between the read / write head and the rapidly rotating platter surface (“ hydrodynamic slide bearing ” - the same effect as with aquaplaning ). In order to keep the heads in position, a constantly high speed of the plate is required. If the speed of rotation drops to too low a value, for example due to a fault in the motor control, the magnetic sensors of the read and write heads can touch the surface of the storage medium.

Other common reasons for head crashes are wear and tear , incorrect installation of the hard disk, strong temperature fluctuations, general vibrations (which occur more frequently in mobile devices, for example with microdrives in digital cameras or notebooks ), operation at too great a height, as well as power failures or soiling on the Plate surfaces.


Destroyed surface of a data disk after a head crash (here: Seagate ).
  • The Autopark function (since the model generations from 1989) automatically parks the heads in the landing zone in the event of a power failure (by using the rotational energy of the plates).
  • To protect against falls, some ThinkPad models have had a motion sensor called APS ( Active Protection System ) since around 2003 , which moves the read / write head of the hard disk into the park position if accelerations are registered that could lead to a head crash.
  • A sudden motion sensor has been installed in Apple laptops since January 2005 , which removes the read / write head from the hard disk when there is strong movement, thus preventing data loss. Some microdrives are also already equipped with a system that detects bumps and immediately brings the read / write heads back to the landing zone.
  • In order to prevent the heads from touching down when the rotation speed is too low, an Airlock system is used in modern hard drives , which parks the heads when the speed is too low.

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