Hitachi Global Storage Technologies Netherlands B.v.

Hidetsugu Tanka

Tetsuo Ueda

Yukio Fukushima

Sachiyo Baba

A method and apparatus for detecting an abnormal fly height of a magnetic head. The method includes reproducing a servo signal recorded on a magnetic disk in advance by the magnetic head when a write operation for writing data on the magnetic disk by the magnetic head is initiated. Next, the gain of the servo signal based on the head part of the servo signal reproduced by the magnetic head is determined. The gain of the servo signal is then compared with a reference value to detect an abnormal fly height of the magnetic head. In an advantageous embodiment, the reference value is the gain of a servo signal determined when the fly height of the magnetic head is normal. Alternatively, in other advantageous embodiments, the reference value is based on the gain of a previous servo signal.

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Fujisawa, Japan

Hidetsugu Tanka