According to one embodiment, a magnetic disk drive comprising, a magnetic disk, a magnetic head, a voice coil motor, and a controller. The controller includes a seek control section, a velocity calculation section, a back electromotive voltage estimation section, and a coil resistance estimation section.

According to one embodiment, a magnetic disk drive comprising, a magnetic disk, a magnetic head, a voice coil motor, and a controller. The controller includes a seek control section, a velocity calculation section, a back electromotive voltage estimation section, and a coil resistance estimation section.

According to one embodiment, a magnetic disk device includes a rotatable disk-shaped recording medium including a plurality of concentric recording tracks, a magnetic head including a write element which writes data to the recording tracks, a heating element, and a sensor which detects a surface condition of the recording medium, and a controller including an inspection circuit which detects, based on an sensor output of the sensor, presence or absence of a bump on a surface of the recording medium, a height and a width of the bump, and a memory which records the detected height and width of the bump.

A magnetic disk device according to an embodiment includes: a magnetic disk including a plurality of tracks; a magnetic head that performs data reading and data writing on the magnetic disk; a plurality of servo regions that is provided in each of the plurality of tracks, and at least partially includes a first physical pattern, the first physical pattern being a physical pattern after writing of a first data pattern including position information of each of the plurality of tracks; and a controller that controls the magnetic head, wherein the plurality of servo regions includes one of a first servo region including the first physical pattern, and a second servo region including a second physical pattern, the second physical pattern being a physical pattern after writing of a second data pattern different from the first data pattern, for each of the plurality of tracks, and the controller performs determination as to which of the first and second physical patterns a third servo region has, the third servo region being one of a servo region among the plurality of servo regions included in the plurality of tracks.

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: generate an expected oscillation spectrum associated with a band of the selected disk; detect oscillation abnormality of the selected head based on comparing an actual oscillation spectrum associated with a data sector in the band to the expected oscillation spectrum associated with the band, wherein the data sector includes data written by the selected head; and perform a remediation action in response to detecting oscillation abnormality of the selected head.

According to one embodiment, a controller of a magnetic disk apparatus operates in a first operation of writing to data regions on a magnetic disk of the magnetic disk apparatus while positioning a magnetic head. In the first operation, the controller demodulates burst patterns to obtain a first burst demodulated value set and corrects the first burst demodulated value set to obtain a second burst demodulated value set. The first burst demodulated value set is corrected on the basis of a correction algorithm using a first set value as an argument. The controller calculates, on the basis of the second burst demodulated value set, an offset amount of the magnetic head from one of servo tracks on the magnetic disk.

According to one embodiment, a magnetic disk device includes a rotatable disk-shaped recording medium including a plurality of concentric recording tracks, a magnetic head including a write element which writes data to the recording tracks, a heating element, and a sensor which detects a surface condition of the recording medium, and a controller including an inspection circuit which detects, based on an sensor output of the sensor, presence or absence of a bump on a surface of the recording medium, a height and a width of the bump, and a memory which records the detected height and width of the bump.

According to one embodiment, during a first write period, an adjustment unit derives a first predicted excess amount and a predicted upper limit threshold value, and a correction limit prediction unit calculates a first cumulative predicted excess amount. The determination unit causes the write processing unit to continue the write processing if determining that the first cumulative predicted excess amount is smaller than or equal to the predicted upper limit threshold value, and causes the write processing unit to suspend the write processing if determining that the first cumulative predicted excess amount exceeds the predicted upper limit threshold value.

A tape drive device includes a head member, a tape drive mechanism moving a tape, a suspension member supporting the head member, piezoelectric units, a drive voltage supply circuit applying a voltage to a piezoelectric element, and a controller. Each of the piezoelectric units includes a piezoelectric element. The controller determines a state of a head unit, based on a piezoelectric output generated at the piezoelectric element provided in the suspension member.

According to one embodiment, a magnetic disk device includes recording layers, write heads, read heads, a selector circuit that allows two or more read heads to be selected from among the read heads, a read target selection unit, a read processing unit, and a detection unit. When the read target selection unit selects the first recording layer and the second recording layer the read processing unit controls driving of the selector circuit and causes the selector circuit to select the first read head and the second read head to read data of the first recording layer and data of the second recording layer simultaneously, and the detection unit detects a state of the first recording layer and a state of the second recording layer.