head crash

falling of the read/write head of a disk onto the magnetic media

A head crash is a specific type of hard disk failure, and occurs when the read-write head of a hard disk drive touches its rotating platter resulting in catastrophic damage to the magnetic media on the platter surface (see Hard disk platter).The head normally rides on a thin film of moving air entrapped at the surface of the platter (some drives of the mid-1990s used a thin fluid layer instead). The topmost layer of the platter is made of a Teflon-like material that acts like a lubricant. Underneath is a layer of sputtered carbon. These two layers protect the magnetic layer (data storage area) from most accidental touches of the read-write head.
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Noun
1. (computer science) a crash of a read/write head in a hard disk drive (usually caused by contact of the head with the surface of the magnetic disk)
(hypernym) crash
(classification) computer science, computing