The magnetic tape includes a non-magnetic support, and a magnetic layer including a ferromagnetic powder. The non-magnetic support is a polyamide support, and a deformation rate ratio of a deformation rate in a width direction to a deformation rate in a longitudinal direction of the magnetic tape, (the deformation rate in the width direction/the deformation rate in the longitudinal direction), is 0.45 or less, the deformation rates each being measured after a load is applied in the longitudinal direction of the magnetic tape for 96 hours.

A magnetic recording medium is a magnetic recording medium having a tape shape and includes a substrate, an underlayer provided on the substrate, and a magnetic layer provided on the underlayer. The magnetic layer has a surface having an uneven shape, a height range ΔH obtained from statistical information of a height of the uneven shape is in a range of 4.00 nm ≤ ΔH ≤ 10.00 nm, and a gradient range ΔA obtained from statistical information of a gradient of the uneven shape is in a range of 2.50 degrees ≤ ΔA.

A magnetic tape device. The angle θ formed by the axis of the element array of the magnetic head with respect to a width direction of the magnetic tape is changed during running of the magnetic tape in the magnetic tape device. The magnetic tape satisfies Equation 1: TDSage+TDSenv−TC≤0.10 μm. In Equation 1, the TDSage is a maximum value of an absolute value of a difference between a servo band spacing obtained before storage for 24 hours in a predetermined environment and a servo band spacing obtained after the storage. TDSenv is a value calculated by multiplying a difference between a maximum value and a minimum value of servo band spacings obtained in each of five predetermined environments by ½, and TC is a value calculated by TC=L{cos (θ.sub.initial−Δθ)−cos (θ.sub.initial+Δθ)}.

A servo writer includes a running unit that sends a tape-like magnetic recording medium out from a cartridge, winds up the sent out magnetic recording medium, and runs the magnetic recording medium; an erasing unit that erases a first servo pattern formed in the magnetic recording medium that runs; a head that writes a servo signal in the running magnetic recording medium from which the first servo pattern is erased and forms a second servo pattern; and a control unit that controls the head so that the servo signal is written in at least one period of an accelerated running period and a decelerated running period of the magnetic recording medium, and forms the second servo pattern that does not satisfy a standard in the magnetic recording medium.

A data storage device is disclosed comprising a head actuated over a disk. A spiral track is written on the disk, and a disk locked clock (DLC) is synchronized to the spiral track. The spiral track is read to generate a spiral track crossing signal, and the spiral track crossing signal is processed to generate a position error signal (PES) representing a position of the head over the disk. When the DLC indicates a first part of the spiral track crossing signal is corrupt, the corruption is compensated in order to generate a compensated PES. While servoing the head over the disk based on the PES, a plurality of concentric servo sectors are written on the disk based on the DLC.

Provided is a magnetic recording medium configured to achieve higher density recording. The magnetic recording medium has a tape-like shape, and includes: a base containing polyester as a main constituent; and a magnetic layer provided on the base, including a plurality of magnetic powders, and configured to record a data signal. An average thickness of the magnetic recording medium is 5.6 μm or less. An average thickness of the base is 4.2 μm or less. An average thickness of the magnetic layer is 90 nm or less. An average aspect ratio of the magnetic powders is 1.0 or greater and 3.0 or less. A coercivity in a perpendicular direction is 3000 oersted or less. A rate of a coercivity in a longitudinal direction to the coercivity in the perpendicular direction is 0.8 or less. The magnetic layer includes a lubricant. An entire BET specific surface area of the magnetic recording medium from which the lubricant has been removed is 2.5 m.sup.2/g or greater.

A magnetic recording medium is a magnetic recording medium having a tape-like shape and includes a base substrate and a magnetic layer provided on the base substrate. A plurality of data tracks can be formed in the magnetic layer, a width of a data track is 2900 nm or less, and in a case of defining, as w.sub.max and w.sub.min, a maximum value and a minimum value respectively out of average values of a width of the magnetic recording medium measured under four kinds of environment in which temperature and relative humidity are set to (10° C., 10%), (10° C., 80%), (29° C., 80%), and (45° C., 10%), w.sub.max and w.sub.min satisfy a relation of (w.sub.max−w.sub.min)/w.sub.min≤400 [ppm].

In the magnetic tape, in a case where a maximum value of an absolute value of a difference between a servo band spacing obtained before storage in an environment of a temperature of 32° C. and relative humidity of 55% and a servo band spacing obtained after storage in the environment for a storage time T is set to A, and T is defined as 24 hours, 48 hours, 72 hours, 96 hours, or 120 hours, a medium life calculated by a linear function of A and a logarithm log.sub.eT of T, that are derived from a value of A and a value of the logarithm log.sub.eT of T obtained for each T is 3 years or longer. The medium life is T in a case where the A satisfies Equation 1: A=1.5−B.

A magnetic tape in which an arithmetic average roughness Ra measured at a surface of the magnetic layer with an atomic force microscope is 2.0 nm or less, and in an environment with a temperature of 23° C. and a relative humidity of 50%, an AlFeSil abrasion value.sub.45° of a surface of the magnetic layer measured at a tilt angle of 45° of an AlFeSil prism is 20 μm to 50 μm, a standard deviation of an AlFeSil abrasion value of the surface of the magnetic layer measured at each of tilt angles of 0°, 15°, 30°, and 45° of the AlFeSil prism is 30 μm or less, and the tilt angle of the AlFeSil prism is an angle formed by a longitudinal direction of the AlFeSil prism and a width direction of the magnetic tape.

In the magnetic tape, a maximum value of magnetic tape deformation amounts after storage in each of five environments for 1 year is 0.50 μm or less, a rate of a change of magnetic tape deformation amount with respect to a change in relative humidity obtained from the five magnetic tape deformation amounts is 0.0001 μm/% to 0.0500 μm/%, and a rate of a change of the magnetic tape deformation amount with respect to a change in temperature obtained from the five magnetic tape deformation amounts is 0.0010 μm/° C. to 0.1000 μm/° C.