Magnetic disk device, control method, and learning method

A control method of controlling a magnetic disk device, the magnetic disk device including a magnetic disk on which tracks are provided, each of the tracks including data areas and a servo area servo areas in which servo information is recorded, the data areas and the servo areas being alternately arranged in a circumferential direction of the magnetic disk, the magnetic disk device including a magnetic head to perform reading and writing from and to the tracks, the control method comprising:

• performing, by using a determination model, a determination on whether or not a distance in a radial direction from a target position related to a first track among the tracks to a position of the magnetic head exceeds a threshold, the position of the magnetic head fluctuating from the target position toward a second track different from the first track among the tracks during execution of writing to the first track, the determination being performed by giving, to the determination model, an input of pieces of position error information including a piece of position error information about one servo area in the first track and obtaining an output value from the determination model in response to the input, the output value indicating whether or not the distance exceeds the threshold while the magnetic head moves in the circumferential direction above the one servo area and one data area between the one servo area and a next servo area;
• performing writing to the one data area of the first track in a case where the output value indicates that the distance does not exceed the threshold;
• and
• performing no writing to the one data area of the first track in a case where the output value indicates that the distance exceeds the threshold,
• wherein the determination model is a machine learning model leaned before the determination by using pieces of position error information obtained by reading the servo information from two or more servo areas and a first true value indicating an actual position of the magnetic head moving in the circumferential direction above the first track including the two or more servo areas.

A learning method implemented by a learning device, the learning method comprising:

• acquiring pieces of position error information obtained by reading servo information from a first track out of tracks provided on a magnetic disk of a magnetic disk device by a magnetic head of the magnetic disk device, the tracks each including data areas and servo areas in which the servo information is recorded, the data areas and the servo areas being alternately arranged in a circumferential direction of the magnetic disk, the magnetic head performing reading and writing from and to the tracks;
• acquiring a first true value indicating an actual position of the magnetic head moving in the circumferential direction above the first track;
• inputting the pieces of position error information to a determination model;
• acquiring an output value output from the determination model;
• and
• learning the determination model by using the first true value,
• wherein the learning the determination model is performed to output an output value, in response to receiving an input of the pieces of position error information, the output value representing whether or not the distance exceeds the threshold while the magnetic head moves in the circumferential direction above one servo area in the first track and one data area between the one servo area and a next servo area.