Method and magnetic disk apparatus

A method comprising:

• acquiring a result of quality inspection related to recording quality of first multiple sectors included in a first storage area of a magnetic disk provided in a magnetic disk apparatus, the first storage area including first multiple tracks to which data is written by a shingled magnetic recording (SMR) scheme, the first multiple tracks each including different sectors out of the first multiple sectors;
• calculating a first number based on a set capacity of the first storage area and a set value of recording density of the first storage area, the first number being a number of sectors corresponding to a capacity obtained by subtracting the set capacity from an actual capacity of the first storage area;
• selecting, based on the result of quality inspection, a second number of sectors from among the first multiple sectors, the second number being a number larger than zero and equal to or smaller than the first number;
• and
• assigning addresses to a group of sectors not included in the second number of sectors among the first multiple sectors, the addresses being usable by a host connected to the magnetic disk apparatus, the group of sectors being sectors with a number corresponding to the set capacity.