Provided is a magnetic tape including: a non-magnetic support; a magnetic layer on one surface side of the non-magnetic support; and a back coating layer on the other surface side, in which a center line average surface roughness Ra measured regarding the surface of the magnetic layer is 1.0 nm to 1.8 nm, the magnetic layer includes ferromagnetic hexagonal ferrite powder and non-magnetic powder, a tilt cos of the ferromagnetic hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation performed by using a scanning transmission electron microscope is 0.85 to 1.00, and logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the back coating layer is equal to or smaller than 0.060.

In one embodiment, a method includes writing a file into a data partition of a tape medium. The method also includes storing a high resolution tape directory (HRTD) having location information of data in the data partition as part of end of data (EOD) of the index partition. The storing the HRTD as part of the EOD of the index partition includes requesting movement of the tape medium to the index partition in order to update an index file after changes have occurred to data in the data partition, and writing an updated index file into the index partition concurrent to writing an updated HRTD into the EOD of the index partition.

A tape device includes a tape drive, a storage unit, and a processor. The tape drive is configured to write plural data units in a magnetic tape formed with plural tracks. The storage unit is configured to store information indicating a reversal position set in a middle of the magnetic tape. The processor is configured to instruct the tape drive to start writing of a first data unit in the magnetic tape. The processor is configured to control the tape drive to continue the writing up to an end of the first data unit when a first write area crosses over the reversal position. The first data unit is written in the first write area. The processor is configured to control the tape drive to change a write destination from the first track to a second track after the first data unit is written and to reverse the write direction.