A ring-shaped spacer is to be arranged in contact with a magnetic disk in a hard disk drive apparatus. A maximum height surface roughness Rz of an outer circumferential edge surface of the spacer is at least 1.5 m, and the spacer is made of amorphous glass.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

An apparatus for changing a record comprising a record changing fork comprising first and second spaced apart tines arranged in a record plane and extending from a fork base to a fork mouth, each tine comprising a groove extending from the fork mouth at least part way to the fork base, the grooves being arranged to hold a record therebetween in the record plane; at least one tine comprising a resiliently deformable record gate, the record gate being adapted to prevent sliding of a record in the grooves past the record gate unless the record is slid with a force exceeding a threshold force; at least one shelf adapted to support a record, the width of the shelf being less than the separation between the tines; and, a control mechanism connected to the record changing fork.

An apparatus for changing a record comprising a record changing fork comprising first and second spaced apart tines arranged in a record plane and extending from a fork base to a fork mouth, each tine comprising a groove extending from the fork mouth at least part way to the fork base, the grooves being arranged to hold a record therebetween in the record plane; at least one tine comprising a resiliently deformable record gate, the record gate being adapted to prevent sliding of a record in the grooves past the record gate unless the record is slid with a force exceeding a threshold force; at least one shelf adapted to support a record, the width of the shelf being less than the separation between the tines; and, a control mechanism connected to the record changing fork.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

When removing magnetic disks and spacers from a hard disk drive apparatus, as necessary, during the assembly of the hard disk drive apparatus, in order to suppress the occurrence of removal failures when removing the spacers using a gripping jig, a surface roughness Rz of an outer circumferential edge surface of a spacer is set to be at least 1.5 m.

According to one embodiment, a magnetic disk device includes a disk medium which has a first region, a second region, and a redundant third region, and a control circuitry. The first region is a region to which first data received from a host is written. The second region is a region to which the first data is temporarily written before the first data is written to the first region. The control circuitry executes defect detection to the first region. Upon detecting a defect, the control circuitry substitutes a first location having the defect in the first region with a second location in the third region. Depending on a total size of free regions of the third region, the control circuitry reallocates a fourth region from the second region to the third region. The fourth region is part or all of the second region.

According to one embodiment, a magnetic disk device includes a disk medium which has a first region, a second region, and a redundant third region, and a control circuitry. The first region is a region to which first data received from a host is written. The second region is a region to which the first data is temporarily written before the first data is written to the first region. The control circuitry executes defect detection to the first region. Upon detecting a defect, the control circuitry substitutes a first location having the defect in the first region with a second location in the third region. Depending on a total size of free regions of the third region, the control circuitry reallocates a fourth region from the second region to the third region. The fourth region is part or all of the second region.

A magnet structure includes first and second magnet units. The first magnet unit is provided with a first magnet fixing section that includes a first surface and a first magnet having a first polarity on the first surface's side. The second magnet unit is provided with a second magnet fixing section that includes a second surface and a second magnet having a second polarity on the second surface's side, the second polarity being an opposite polarity to the first polarity. The first and second surfaces are located next to one another on the same plane to form a magnetic attachment surface which is magnetically attached to a magnetically-attached object. The second magnet unit is supported by the first magnet unit so as to move in a predetermined range.