Recording density setting method and magnetic disk device

Abstract

According to one embodiment, a recording density setting method includes performing first process and performing second process. The first process including recording and reading data on and from a disk medium of a magnetic disk device, and acquiring first information for setting the read data to satisfy a certain quality criterion. The first information represents a first shape of a first plurality of unit regions. Each of the a first plurality of unit regions is a recording region of a unit capacity. The second process includes acquiring second information representing a second shape of the first plurality of unit regions, and setting a recording density on the basis of the second information. The second shape is formed by adding margin regions having the same area to the first plurality of unit regions of the first shape.

What is claimed is: 
     
         1 . A magnetic disk device, comprising:
 a disk medium including a first partial region and a second partial region, each of the first and second partial regions including a plurality of unit regions each of which is a recording region of a unit capacity, wherein   an area of the margin region of an unit region in the first partial region is equal to an area of the margin region of an unit region in the second partial region.   
     
     
         2 . The magnetic disk device according to  claim 1 , wherein
 the unit capacity is a capacity of 1 bit,   a track pitch and a bit are set for each of the first and second partial regions,   the area of the margin region of the unit region in the first partial region corresponds to a value obtained by multiplying a first value by a second value,
 the first value being a bit pitch set for the first partial region, 
 the second value being a value obtained by subtracting a third value from a fourth value, 
 the third value being a value of a track pitch to make a sector error rate at a time of reading data that is recorded with a bit pitch of the first value in the first partial region, 
 the fourth value being a track pitch set for the first partial region, 
   the area of the margin region of the unit region in the second partial region corresponds to a value obtained by multiplying a sixth value by a seventh value,
 the sixth value being a bit pitch set for the second partial region, 
 the seventh value being a value obtained by subtracting an eighth value from a ninth value, 
 the eighth value being a value of a track pitch to make a sector error rate at a time of reading data that is recorded with a bit pitch of the sixth value in the second partial region, 
 the ninth value being a track pitch set for the second partial region. 
   
     
     
         3 . The magnetic disk device according to  claim 1  further comprising a magnetic head, wherein
 the magnetic head records data into the first and second partial regions by shingled magnetic recording. 
 
     
     
         4 . The magnetic disk device according to  claim 1 , wherein
 the disk medium has a recording surface,   the recording surface is divided into a plurality of partial regions in a radial direction of the disk medium,   the first partial region is one of the plurality of partial regions, and   the second partial region is another of the plurality of partial regions.   
     
     
         5 . A magnetic disk device, comprising:
 a disk medium including partial regions, each of the partial regions including a plurality of unit regions each of which is a recording region of a unit capacity, wherein   an area of the margin region of an unit region in each partial region is uniform for all of the partial regions.   
     
     
         6 . The magnetic disk device according to  claim 5 , wherein
 the unit capacity is a capacity of 1 bit,   a track pitch and a bit are set for each of the partial regions,   the area of the margin region corresponds to a value obtained by multiplying a first value by a second value,
 the first value being a set value of a bit pitch, 
 the second value being a value obtained by subtracting a third value from a fourth value, 
 the third value being a value of a track pitch to make a sector error rate at a time of reading data that is recorded with a bit pitch of the first value, 
 the fourth value being a set value of a track pitch. 
   
     
     
         7 . The magnetic disk device according to  claim 6  further comprising a magnetic head, wherein
 the magnetic head records data into each of the part