Abstract: According to one embodiment, a magnetic disk device includes a disk, a first head, and a control unit. The control unit includes an adjustment unit capable of adjusting k1, a counter, a determination unit, and a refresh processing unit. The adjustment unit adjusts the k1 to a numerical value within a first range during a first period, and adjusts the k1 to a numerical value within a second range during a second period. The upper limit of the numerical value within the second range is smaller than a lower limit of the numerical value within the first range.

Abstract: According to one embodiment, when an access destination of a reading request is a second region, a controller performs a first retry reading process by use of a second reading condition in first parameter information. The second region is adjacent to a first region, which is adjacent to a defect region and has a particular width, and is present as a region other than the defect region on a magnetic disk. When the access destination of the reading request is the first region, the controller performs a second retry reading process by use of a fourth reading condition in second parameter information. The second parameter information is set such that a grown defect is registered at an earlier time in the second retry reading process, as compared with that in the first retry reading process.

Abstract: According to one embodiment, there is provided a magnetic disk device including a magnetic head and a controller. The magnetic head includes a write head and a read head. The controller is configured to measure a difference amount for each of a first track and a second track near the first track on a magnetic disk. The difference amount is a difference between an actual read/write offset and a read/write offset set as an amount corresponding to a distance between the write head and the read head in a cross track direction. The controller is configured to identify a track having an abnormal track pitch based on the measured difference amount.

Abstract: According to one embodiment, an information recording device includes: a magnetic recording medium having tracks; a detector configured to detect widths of fringing phenomena that occur on both sides, in a track arrangement direction, of a track during recording on the track; and a recording controller configured to control recording so that adjacent tracks overlap with each other and that a track pitch is set at least on the basis of a smaller one of the detected fringing widths and a data read width for reading of data from the track.

Abstract: An information recording device includes: a magnetic disk; an identify module; and a record module. The magnetic disk includes information tracks for recording information by a shingle recording method and an alternate track including an alternate sector for recording alternate information. The identify module is configured to identify a track group including the information tracks that includes update sectors for updating information and a defective sector. The record module is configured to perform recording for updating information on the identified track group without updating the alternate information of the alternate sector corresponding to the defective sector.