Abstract: According to one embodiment, a disk device includes a magnetic disk and a control circuit. The magnetic disk includes a shingled magnetic recording (SMR) region where data is recorded such that adjacent tracks are partially overlapped with each other by SMR. The control circuit writes, at a predetermined timing, dummy data to a location on the magnetic disk. The location is located after a position indicated by a write pointer. The control circuit executes scan processing after the writing of the dummy data.

Abstract: According to one embodiment, a magnetic disk drive includes a disk, a determination module, and a controller. The determination module is configured to determine whether access to the disk requires data transfer between a host and the magnetic disk drive in accessing the disk. The controller is configured to control disk access according to a predetermined allocation of consecutive second logical addresses corresponding to physical addresses indicative of consecutive physical locations on the disk if the data transfer is not required. The second logical addresses are addresses different from first logical addresses recognized by the host.

Abstract: According to one embodiment, a magnetic disk apparatus comprises a magnetic disk configured to store encrypted data, a magnetic head configured to read data from and to write data to the magnetic disk, and a recording and reproducing circuit connected to the magnetic head, wherein the recording and reproducing circuit configured to read data from an area of the magnetic disk, to decrypt read data, to re-encrypt decrypted data with changing a cipher key, and to rewrite re-encrypted data in the area of the magnetic disk.

Abstract: According to one embodiment, a magnetic disk apparatus comprises a storage-medium unit including a storage medium, a magnetic-disk medium unit including a magnetic disk medium, a storing unit configured to store data transmitted from a host system in the storage medium, a first comparator configured to compare an input password with a password stored in the storage medium or in a semiconductor memory provided on a substrate on which the storage medium is provided, and a control unit provided in the storage-medium unit and configured to control an access to the magnetic disk medium in accordance with a comparison result obtained by the first comparator.

Abstract: A hang-up detector and an interrupt generator are provided in a disk controller incorporated in a disk storage system. By monitoring a command execution period, the detector detects whether the disk storage system reaches a hang-up state during the execution of a command in the system. The interrupt generator generates an interrupt to a CPU when the detector has detected the hang-up state. Upon receiving the interrupt, the CPU executes control for re-executing the command.

Abstract: A hang-up detector and an interrupt generator are provided in a disk controller incorporated in a disk storage system. By monitoring a command execution period, the detector detects whether the disk storage system reaches a hang-up state during the execution of a command in the system. The interrupt generator generates an interrupt to a CPU when the detector has detected the hang-up state. Upon receiving the interrupt, the CPU executes control for re-executing the command.

Abstract: A CPU increments the variation in the corresponding monitor value in a monitor value storage area secured in a RAM, each time an event to be monitored has occurred. When the monitor value must be stored, the CPU adds the incremented one of the variations in the individual monitor values stored in the monitor value storage area to the corresponding value in a monitor value saving area secured in the system area of the disk, executes monitor value saving control by which the monitor value is replaced with the resulting monitor value, and then clears the monitor value storage area.

Abstract: A buffer memory is prepared to temporarily store data sequentially read out from consecutive storage positions of a magnetic disk. When a read request is received from a host system, and an HDC reads out the requested data from the magnetic disk, the readout data is written in a buffer area in the buffer memory, which is assigned by a CPU and designated by a buffer management data portion, from the start position to the end position of the area. If the requested data exceeds the capacity of this area, the start address returns to a position indicated by a new start buffer address set in the buffer management data portion which is set by the CPU, e.g., a middle point in the buffer area, and the succeeding readout data is stored in the buffer area from the middle point to the end position. The requested data stored in the buffer memory is sequentially transferred to the host system.