Abstract: According to one embodiment, a disk medium rotates in a first rotation state when access is given, and rotates in a second rotation state lower in rotation number than the first rotation state when access is not given. A controller receives, from a host device, a read command for reading first data stored in a first buffer, when the disk medium is in the second rotation state. The controller transmits the first data from the first buffer to the host device, without causing a shift into the first rotation state, and then shifts the disk medium into the first rotation state after completion of execution of the read command.

Abstract: According to one embodiment, a disk medium rotates in a first rotation state when access is given, and rotates in a second rotation state lower in rotation number than the first rotation state when access is not given. A controller receives, from a host device, a read command for reading first data stored in a first buffer, when the disk medium is in the second rotation state. The controller transmits the first data from the first buffer to the host device, without causing a shift into the first rotation state, and then shifts the disk medium into the first rotation state after completion of execution of the read command.

Abstract: According to one embodiment, there is provided a disk apparatus including a disk medium, a nonvolatile memory, and a controller. In the nonvolatile memory, data to be recorded to the disk medium is written. The controller is configured to perform, according to amount of free space of the nonvolatile memory, write process of the data in the nonvolatile memory collectively, or in multiple times with dividing the write process.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, a read/write apparatus includes a receiver and a refresh module. The receiver receives a write command requesting a write to a magnetic disk. The refresh module refreshes, when a first area of the magnetic disk includes a second area corresponding to the write command, data written in a third area, the third area being an area obtained by excluding the second area from the first area.

Abstract: According to one embodiment, a read/write apparatus includes a receiver and a refresh module. The receiver receives a write command requesting a write to a magnetic disk. The refresh module refreshes, when a first area of the magnetic disk includes a second area corresponding to the write command, data written in a third area, the third area being an area obtained by excluding the second area from the first area.

Abstract: A disk storage device stores write data in a cache area of a data buffer according to a write command from a host, reports write completion to the host, and then writes the write data in the cache area to a storage medium. The disk storage device stores the write data stored in the data buffer in a save area created on the storage disk in response to the reception of a command which requires integrity, other than a write command, and reports a response to the host. Therefore processing time of this command and response time to the host can be decreased, while maintaining the safety of the write data.

Abstract: A disk storage device stores write data in a cache area of a data buffer according to a write command from a host, reports write completion to the host, and then writes the write data in the cache area to a storage medium. The disk storage device stores the write data stored in the data buffer in a save area created on the storage disk in response to the reception of a command which requires integrity, other than a write command, and reports a response to the host. Therefore processing time of this command and response time to the host can be decreased, while maintaining the safety of the write data.

Abstract: The write cache control unit stores data in the buffer memory in response to a write command from a higher-level apparatus to respond a normal ending of the command, and then writes the data in the buffer memory on the disk medium. The vibratory environment measuring unit measures an environment under which a vibration is applied to the apparatus. When an abnormal vibratory environment under which writing on the disk medium likely fails is determined from a measured environment by the vibratory environment measuring unit, the vibration countermeasure processing unit disables the write cache control unit, and if the write cache data remains in the buffer memory at that time, writes the data in the temporary storage area, and if the abnormal vibratory environment is not determined, writes back the data to the original position on the disk medium.