Embodiments relate to a polishing composition is an aqueous composition containing at least colloidal silica, wet-process silica particles, and a water-soluble polymer compound. The water-soluble polymer compound is a copolymer containing a monomer having a carboxylic acid group, a monomer having an amide group, and a monomer having a sulfonic acid group as essential monomers.

Embodiments provide a polishing composition for a magnetic disk substrate containing colloidal silica, a water-soluble polymer, and water. The water-soluble polymer compound is a copolymer containing a monomer having a carboxylic acid group, a monomer having an amide group, and a monomer having a sulfonic acid group as essential monomers. The water-soluble polymer compound has a weight average molecular weight of 1,000 to 1,000,000.

A magnetic disk device includes a disk, a head configured to write data on the disk based on a write current, and a controller configured to determine whether a write error occurs when data is written on the disk, based on a change in a heating value of the head, and upon determining that the write error occurs, read the data written on the disk.

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a first sensor element and a second sensor element. When configured into a first single-ended mode, a bias signal is applied to the first sensor element to generate a first single-ended output signal based on a response of the first sensor element, and when configured into a second single-ended mode, the bias signal is applied to the second sensor element to generate a second single-ended output signal based on a response of the first sensor element. When configured into a differential mode, the bias signal is concurrently applied to the first sensor element and the second sensor element to generate a differential output signal based on a response of the first sensor element and the second sensor element.

According to one embodiment, a disk device includes two magnetic disks opposing each other at intervals of 1.2 to 1.5 mm, and at least two suspension assemblies movable respectively between the two magnetic disks. Each of the suspension assemblies includes a base plate, a load beam extending from the base plate, a tab extending from a distal end of the load beam, a wiring member on the load beam and the base plate, including a gimbal portion, and a magnetic head on the gimbal portion, abutting on a dimple of the load beam via the gimbal portion. The ratio of a distance from a bendable location of the load beam to a center of the dimple with respect to a distance from the center of the dimple to a tip of the tab is 2.8 to 3.8.

According to one embodiment, a disk device includes two magnetic disks opposing each other at intervals of 1.2 to 1.5 mm, and at least two suspension assemblies movable respectively between the two magnetic disks. Each of the suspension assemblies includes a base plate, a load beam extending from the base plate, a tab extending from a distal end of the load beam, a wiring member on the load beam and the base plate, including a gimbal portion, and a magnetic head on the gimbal portion, abutting on a dimple of the load beam via the gimbal portion. The ratio of a distance from a bendable location of the load beam to a center of the dimple with respect to a distance from the center of the dimple to a tip of the tab is 2.8 to 3.8.

A method according to one embodiment includes acquiring a result of quality inspection related to recording quality of first sectors included in a first storage area of a magnetic disk. The method includes calculating a first number being the number of sectors corresponding to a capacity obtained by subtracting a set capacity from an actual capacity of the first storage area. The first number is calculated based on the set capacity of the first storage area and a set value of recording density of the first storage area. The method includes selecting a second number of sectors from the first sectors based on the result of quality inspection. The method includes assigning addresses to a group of sectors that are not included in the second number of sectors among the first sectors. The group of sectors consists of sectors with the number corresponding to the set capacity.

According to one embodiment, a disk device includes two magnetic disks opposing each other at intervals of 1.2 to 1.5 mm, and at least two suspension assemblies movable respectively between the two magnetic disks. Each of the suspension assemblies includes a base plate, a load beam extending from the base plate, a tab extending from a distal end of the load beam, a wiring member on the load beam and the base plate, including a gimbal portion, and a magnetic head on the gimbal portion, abutting on a dimple of the load beam via the gimbal portion. The ratio of a distance from a bendable location of the load beam to a center of the dimple with respect to a distance from the center of the dimple to a tip of the tab is 2.8 to 3.8.