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, on a first track of a magnetic disk, a plurality of first sectors in each of which a data segment is stored, and a second sector in which a parity for first error correction is stored are arranged in this order from a first position. A controller executes a first operation of sequentially reading a first data segment from each of the plurality of first sectors, and storing a group of the read first data segments in a buffer memory. The controller obtains a first parity from the group of the read first data segments. The controller starts a second operation of writing each first data segment stored in the buffer memory, to a first sector that is a read source among the plurality of first sectors, and writing the first parity to the second sector, before the magnetic head reaches the first position.

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, on a first track of a magnetic disk, a plurality of first sectors in each of which a data segment is stored, and a second sector in which a parity for first error correction is stored are arranged in this order from a first position. A controller executes a first operation of sequentially reading a first data segment from each of the plurality of first sectors, and storing a group of the read first data segments in a buffer memory. The controller obtains a first parity from the group of the read first data segments. The controller starts a second operation of writing each first data segment in the group of the first data segments stored in the buffer memory, to a first sector that is a read source among the plurality of first sectors, and writing the first parity to the second sector, before the magnetic head reaches the first position.

Abstract: According to one embodiment, a magnetic disk device includes a disk including a first area where user data is written and a second area which is different from the first area, a head configured to write data to the disk and read data from the disk, and a controller configured to generate, when a first sector of a first track, which includes a first parity sector and the first sector which is different from the first parity sector in the first area, is reassigned to a second track in the second area, a second parity sector corresponding to the first sector.

Abstract: A magnetic disk device includes a plurality of tracks and a controller. The controller receives write data to be written to a first sector of a track, generates a first data string based on the write data and a logical identifier for the first sector, attempts to cause the first data string to be written to the first sector, determines whether a write error has occurred while the first data string is written to the first sector, generates a second data string based at least in part on the first data string, and in response to determining that no write error has occurred while the first data string is written to the first sector, writes a parity data string that is based at least in part on the second data string to a second sector of the track that stores parity data for the track.

Abstract: A disk device includes a recording medium on which data is recorded, a decoding circuit configured to decode data read from the recording medium, and a control circuit. The control circuit is configured to cause first data associated with a target sector referenced in a read request to be read from a target track of the recording medium, second data associated with a non-target sector that is not referenced in the read request to be read from the recording medium after the first data is read from the recording medium, and decoding of the first data to be completed by the decoding circuit after the second data is read from the recording medium.

Abstract: A magnetic disk device includes a plurality of tracks and a controller. The controller receives write data to be written to a first sector of a track, generates a first data string based on the write data and a logical identifier for the first sector, attempts to cause the first data string to be written to the first sector, determines whether a write error has occurred while the first data string is written to the first sector, generates a second data string based at least in part on the first data string, and in response to determining that no write error has occurred while the first data string is written to the first sector, writes a parity data string that is based at least in part on the second data string to a second sector of the track that stores parity data for the track.

Abstract: A disk device includes a recording medium on which data is recorded, a decoding circuit configured to decode data read from the recording medium, and a control circuit. The control circuit is configured to cause first data associated with a target sector referenced in a read request to be read from a target track of the recording medium, second data associated with a non-target sector that is not referenced in the read request to be read from the recording medium after the first data is read from the recording medium, and decoding of the first data to be completed by the decoding circuit after the second data is read from the recording medium.

Abstract: A disk device includes a recording medium on which data is recorded, a decoding circuit configured to decode data read from the recording medium, and a control circuit. The control circuit is configured to cause first data associated with a target sector referenced in a read request to be read from a target track of the recording medium, second data associated with a non-target sector that is not referenced in the read request to be read from the recording medium after the first data is read from the recording medium, and decoding of the first data to be completed by the decoding circuit after the second data is read from the recording medium.

Abstract: A disk device includes a recording medium on which data is recorded, a decoding circuit configured to decode data read from the recording medium, and a control circuit. The control circuit is configured to cause first data associated with a target sector referenced in a read request to be read from a target track of the recording medium, second data associated with a non-target sector that is not referenced in the read request to be read from the recording medium after the first data is read from the recording medium, and decoding of the first data to be completed by the decoding circuit after the second data is read from the recording medium.