Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Tetsuo Kuribayashi

Hironori Kanno

Michio Yamamoto

Takumi Kakuya

Masami Tashiro

Kenji Inoue

Keiichi Yorimitsu

Seiji Toda

Takuya Mori

Nobuhiro Sugawara

Kazuo Chokki

Hidekazu Masuyama

Kenji Ogawa

Takahiro Kawai

According to one embodiment, a magnetic disk device includes a disk, a storage section, a first determination unit, and a first parity management unit. The first determination unit determines presence or absence of an unexecuted command. The first parity management unit searches the storage section for the first parity area after the first determination unit determines that there is no unexecuted command. The first parity management unit generates the first parity based on the first data in the first data area if the first parity area is detected as the invalid parity area, and writes the first parity to the first parity area.

Magnetic disk device and method of managing parity

According to one embodiment, a magnetic disk device includes a memory and a controller. The memory stores, for a predetermined track on a magnetic disk in the device, a counter, a counter threshold, and weights. The weights are individually set for divided areas of the predetermined track. The weights each have magnitude inversely proportional to a guaranteed number of times of data readout. When writing to an adjacent track of one or more of the divided areas is executed, the controller multiplies a number of times of writing by the weight corresponding to the one or more of the divided areas and adds the number of times of writing to the counter. When a numerical value of the counter reaches the counter threshold, the controller executes refresh to rewrite data in the predetermined track or executes reading for determining whether or not to perform the refresh.

Magnetic disk device and control method

According to one embodiment, a magnetic disk drive selects in command evaluation in reordering processing, a command accessible in a shortest time. The device determines whether media bumps which influence a dynamic flying height (DFH) control exist in a seek section between completion of a previous command and start of a selected command or not, calculates a latency necessary for avoidance of the media bumps if it is determined by the determination that the media bumps which influence the DFH control exist, and selects the command accessible in the shortest time including the time obtained by summing the latency calculated by the calculation as the command to be next processed.

Magnetic head control capable of avoidance media bumps during seeking process

According to one embodiment, there is provided a magnetic disk device including a magnetic disk, a storage unit, and a control unit. The magnetic disk includes a recording region. The storage unit is configured to store a value according to number of accesses to each of a plurality of regions obtained by dividing of the recording region of the magnetic disk in association with each of the plurality of regions. The control unit is configured to count a value according to the number of accesses to each of a plurality of regions in a count step unit that is a value determined according to an elapsed time from occurrence of a specific situation and is a value counted per unit access, and to update the value stored in the storage unit.

Magnetic disk device

According to one embodiment, any of a first process to perform a write retry to a write target track, a second process to perform the write retry and perform reading for data verification to an adjacent track, and a third process to perform the write retry and write data of the adjacent track to another track is executed based on a result of comparison between an offtrack amount and a plurality of different slice values.

Magnetic disk device and control method of magnetic disk

An information recording device includes a recording medium that includes a data area, and a controller that controls recording of data on the recording medium, wherein in response to a request for execution of formatting of the data area of the recording medium, the controller does not record data for the formatting in the data area and records format information about the formatting in a nonvolatile recording area that is different from the data area.

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Yokohama Kanagawa, Japan

Tetsuo Kuribayashi