Abstract: According to an embodiment, a track includes first sectors and a second sector. When write of a second data segment to a third sector that is one of the first sectors is requested from a host, a controller acquires the second data segment from the host and stores the second data segment in the memory, and reads a data set including all first data segments and all first information pieces from the track and stores the data set in the memory. The controller acquires a second information piece of the third sector, and updates a first data segment and a first information piece read from the third sector in the data set in the memory with the second data segment and the second information piece. The controller calculates a second parity while the updated data set to the track, and writes the second parity to the second sector.

Abstract: According to an embodiment, a track includes first sectors and a second sector. When write of a second data segment to a third sector that is one of the first sectors is requested from a host, a controller acquires the second data segment from the host and stores the second data segment in the memory, and reads a data set including all first data segments and all first information pieces from the track and stores the data set in the memory. The controller acquires a second information piece of the third sector, and updates a first data segment and a first information piece read from the third sector in the data set in the memory with the second data segment and the second information piece. The controller calculates a second parity while the updated data set to the track, and writes the second parity to the second sector.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a first magnetic head, a second magnetic head, a buffer memory, and a control circuit. The magnetic disk includes a plurality of first storage regions. The control circuit controls the first magnetic head to read first data from a second storage region of the first storage regions to the buffer memory. The control circuit controls the second magnetic head to write second data to a third storage region concurrently with the reading of the first data. The third region is of the first storage regions, different from the second storage region. The second data corresponds to the first data stored in the buffer memory.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk including a plurality of tracks, first and second actuators, and a control circuit. The magnetic disk includes the plurality of tracks. The control circuit writes, in a first track by using the first actuator, second data having a size corresponding to a first number among the first data. In addition, the control circuit writes, in a second track by using the second actuator, third data having a size corresponding to a second number among the first data. Each of the first track and the second track is a track among the plurality of tracks. The first number is a number of writable sectors included in the first track. The second number is a number of writable sectors included in the second track. The third data is data received subsequent to the second data.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk including a plurality of tracks, first and second actuators, and a control circuit. The magnetic disk includes the plurality of tracks. The control circuit writes, in a first track by using the first actuator, second data having a size corresponding to a first number among the first data. In addition, the control circuit writes, in a second track by using the second actuator, third data having a size corresponding to a second number among the first data. Each of the first track and the second track is a track among the plurality of tracks. The first number is a number of writable sectors included in the first track. The second number is a number of writable sectors included in the second track. The third data is data received subsequent to the second data.

Abstract: According to one embodiment, a magnetic disk device includes a memory including a first storage area and a second storage area different from the first storage area, and a controller configured to generate a compressed data compressing input data, generate a header data related to a compressed data group including a plurality of compressed data, generate a packet data including the compressed data group and the header data, store the packet data in the first storage area, and store the header data in the second storage area.

Abstract: According to one embodiment, a magnetic disk device includes a memory including a first storage area and a second storage area different from the first storage area, and a controller configured to generate a compressed data compressing input data, generate a header data related to a compressed data group including a plurality of compressed data, generate a packet data including the compressed data group and the header data, store the packet data in the first storage area, and store the header data in the second storage area.

Abstract: According to one embodiment, a storage control apparatus includes a first buffer controller and a second buffer controller. The first buffer controller is configured to store data of a first unit in each of data buffer regions, and the data of the first unit is transmitted from a host and written in a nonvolatile memory, or read from the nonvolatile memory and transmitted to the host. The second buffer controller is configured to independently transmit data of a second unit from the data buffer region corresponding to a bank prepared for transmission when data is written in the nonvolatile memory, and to independently transmit data of the second unit from a bank to be read to the data buffer region corresponding to the bank to be read when data is transmitted to the host.

Abstract: According to one embodiment, when a command has been detected, while data transfer is in progress, it is determined that the command has been unintentionally issued, and a mode move is limited. A control apparatus has a command decoder circuit, a data control circuit, a state control circuit which analyzes the content of the command, and then, controls states of the data control circuit and a memory unit, a detecting unit which detects a command indicating a state move, a data transfer state determining unit which, when the command has been detected, determines whether or not the data control unit is in data transfer, and a move mode setting unit which, when the data transfer state determining unit is in data transfer, moves an operating mode to an idle state.