Hitachi Global Storage Technologies Netherlands B.v.

Iwao Oshimi

Gaku Ikedo

Jiro Abe

Nobuhisa Koide

Sumie Takeda

Katsumoto Onoyama

Hiroyuki Oosawa

Embodiments of the present invention prevent occurrence of a write pole erasure in the event of a power failure within a magnetic disk apparatus of a perpendicular magnetic recording system. According to one embodiment of the present invention, a recording current is flowed through a magnetic head to record data in a magnetic disk. An occurrence of a power failure in the magnetic disk apparatus is detected. When a power failure has occurred, the recording head is demagnetized with power in case of a power failure. The recording head is unloaded after the recording head has been demagnetized. For the power in case of a power failure, back electromotive force of a spindle motor can be utilized. As a result, effects exerted on data recorded in the magnetic disk due to residual magnetism remaining in the recording head can be eliminated.

Recording method, unload method, and magnetic disk

Embodiments of the present invention provide a magnetic disk device including a spindle motor using a fluid dynamic bearing, which can send back READY within a period requested by a host system at the time of starting a magnetic disk device under low temperature and low supply voltage conditions without a particular heating approach. According to one embodiment, the magnetic disk device sets a waiting time in a period from when a spindle motor reaches a rated speed until when an HSA is loaded to a magnetic disk at the time of starting under low temperature and low supply voltage conditions within such a range that the timeout of the host does not occur, and the spindle motor itself is heated by rotation of the spindle motor in the waiting time to lower viscosity of the lubrication fluid to ensure sufficient voltage margin for an SPM driver.

Method of starting the magnetic disk device using fluid dynamic bearing spindle motor

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Kanagawa, Japan

Iwao Oshimi