According to one embodiment, a magnetic disk device includes a disk, a head, and a controller that sets at least a set of a first target position and a second target position to be matched, among a plurality of the first target positions respectively corresponding to a plurality of first tracks in a case where writing on the first tracks is performed to the first region of the disk in a radial direction of the disk under a first recording mode, and a plurality of the second target positions respectively corresponding to a plurality of second tracks in a case where writing on the second tracks is performed to the first region in the radial direction under a second recording mode different from the first recording mode.

Provided are a tape drive, tape drive controller, and method for measuring amplitudes of written tracks to determine errors in read and write elements. The write element writes a data pattern and erase pattern to the tape medium to provide the data pattern and the erase pattern on sides of the data pattern. The read element is positioned to measure amplitudes at offsets in the data pattern. The offsets and the amplitudes at the offsets are processed to estimate a maximum amplitude read while the read element is estimated to be positioned entirely in the data pattern and estimate an offset at which the read element reads a fixed percentage of the maximum amplitude. A width of the read element is estimated based on the estimated offset. The estimated width of the read element is outputted to determine whether the estimated width of the read element is acceptable.

According to one embodiment, a magnetic disk device includes a disk, a head that has a write head that writes data to the disk and a read head that reads data from the disk, and a controller that changes an offset amount during read processing according to a vibration applied by a disturbance.

A controller for a magnetic disk device acquires a reproduction signal of servo burst data while moving a magnetic head along data tracks that intersect servo tracks at a plurality of points. The controller acquires correction values for correcting repeatable runout on a per servo sector basis based on the reproduction signal. The correction values include a first correction value, which is a correction value for a servo sector at a position where the data track and the servo track are substantially parallel to each other and a second correction value, which is a correction value fora servo sector at a position where the data track and the servo track are not substantially parallel to each other. The controller adjusts the first correction value based on the second correction value, and writes the correction values including the adjusted first correction value onto a magnetic disk.

The technology disclosed herein pertains to a method for determining expected command completion time (CCT), the method including receiving a plurality of position error signals (PESs) for an HDD over a predetermined time period, determining sigma of the plurality of PESs, retrieving upper off-track limits (UOL) for one or more data sectors of the HDD, calculating average number of retrieved sectors (A) between two consecutive occurrences of the |PES|>UOL for the HDD, and determining required number of revolutions (CCT) to collect data based on the average number of retrieved data sectors (A) and a total number of requested data sectors (N).

Generating a hard disk drive (HDD) data track repeatable runout (RRO) compensation value for a target track involves querying at least one RRO table for a closest track to the target track external servo target (EST) and identifying an EST.sub.x corresponding to the closest track, computing a first absolute value of the difference between the EST and the EST.sub.x, and responsive to the first absolute value being less than an approximation threshold, setting the RRO compensation value for the target track to the RRO compensation value for the closest track. Else, querying the RRO table(s) for each adjacent track to the target track, computing the difference between the ESTs for the adjacent tracks, and responsive to the second absolute value being less than an interpolation threshold, determining an RRO compensation value for the target track based on RRO compensation values corresponding to the adjacent tracks.

A data storage device is disclosed comprising at least one head configured to access a magnetic tape comprising a plurality of servo frames each comprising a plurality of servo bursts, wherein each servo burst comprises a plurality of servo stripes. The servo stripes in a first servo burst are read using the head to generate a first read signal that is processed using a first matched filter matched to the first servo burst in order to generate an average time stamp for the servo stripes in the first servo burst. A position error signal (PES) is generated based on the average time stamp of the first servo burst, and the head is positioned relative to the magnetic tape based on the PES.

According to one embodiment, a method for manufacturing a magnetic disk device includes: moving a magnetic head such that a read head is located on a first learning position among a plurality of learning positions set in a radial direction of a magnetic disk; and learning RRO correction information related to the first learning position using the read head. The method further includes: moving the magnetic head such that the read head is located on a second learning position among the plurality of learning positions; and executing writing of the RRO correction information related to the first learning position using the write head in parallel while learning RRO correction information related to the second learning position using the read head when the read head is located on the second learning position.

A data storage device is disclosed comprising at least one head configured to access a magnetic tape comprising a plurality of servo frames each comprising a plurality of servo stripes. The servo stripes are read using the head to generate a read signal that is processed to generate a position error signal (PES). The head is positioned relative to the magnetic tape based on the PES, and the read signal is demodulated into digital data based on a number of servo stripes detected in each servo frame.

A data storage device is disclosed comprising at least one head configured to access a magnetic tape comprising a plurality of servo frames each comprising a plurality of servo stripes. The servo stripes are read using the head to generate a read signal that is processed to generate a position error signal (PES). The head is positioned relative to the magnetic tape based on the PES, and the read signal is demodulated into digital data based on a number of servo stripes detected in each servo frame.