Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: According to one embodiment, there is provided an information-processing device which includes a storage medium and a controller configured to acquire a delay time in access to storage area included in the storage medium for every storage area with reference to a time at which an access is performed without performing retrying on the storage area based on first information relating to an access history with respect to the storage area, and to determine the storage area of which the delay time exceeds a predetermined allowable delay time as a defective area.

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 of the present invention, a cache control method of a storage device is provided, the storage device including: a storage unit that stores data, and a buffer memory having a first cache area and a second cache area serving as a cache of the storage unit. The cache control method according to the embodiment includes: storing data read from the storage unit in the first cache area in response to a read command from a host; moving retried data, on which a read retry has occurred upon the readout from the storage unit, to the second cache area from the first cache area in order that the retried data amount in the second cache area is not more than a predetermined data amount; and transferring data in the first cache area or the second cache area to the host.

Abstract: 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.

Abstract: A disk clamp includes a flat plate. A receiving hole penetrates through the flat plate. Through holes penetrate through the flat plate on an imaginary circle defined around the longitudinal center axis of the receiving hole. Depressions are formed on the front surface of the flat plate at positions between the through holes. The disk clamp is mounted on a rotor of the spindle motor, for example. A screw is received in a screw bore formed in the flat plate when the disk clamp is mounted on the rotor. The screw is screwed into the rotor. A disk medium is mounted on the spindle motor. In the process of screwing, a jig is inserted in the through hole. The jig is received in a bottomed hole formed in the rotor. The jig serves to restrict relative rotation between the disk clamp and the rotor.