Magnetic disk apparatus

A magnetic disk apparatus comprising:

• a magnetic disk on which tracks are provided, the tracks including servo sectors in which servo information is recorded, the servo sectors being arranged at intervals in a circumferential direction of the magnetic disk, each of the tracks including long-distance sectors, each of the long-distance sectors being a region in which data is written and being a region having a length in the circumferential direction over two or more servo sectors of the servo sectors, the tracks including a first track and a second track, the second track being adjacent to the first track in a radial direction of the magnetic disk and being subjected to write before the first track;
• a magnetic head configured to write and read data to and from the magnetic disk;
• and
• a controller configured to
• calculate a first threshold individually for each of first long-distance sectors, which are the long-distance sectors provided in the second track, the first threshold being calculated based on quality of each of the first long-distance sectors,
• in a write operation on a first part on the first track, the first part being a part adjacent to a second part, the second part being a part between two ends of a second long-distance sector in the circumferential direction, the second long-distance sector being one of the first long-distance sectors,
• calculate squeeze amounts at first positions in the circumferential direction included in the second long-distance sector based on the servo information read from one or more of the servo sectors where the magnetic head passes over among the two or more of the servo sectors included in the first part, the squeeze amounts each being a narrowed amount of a width of the second track from a design value caused by the write operation,
• compare a total value of the squeeze amounts at the first positions with the first threshold for the second long-distance sector, and
• perform interruption of the write operation and perform a protection operation of protecting data of the second track, based on a comparison result between the total value and the first threshold for the second long-distance sector.

A magnetic disk apparatus comprising:

• a magnetic disk on which tracks are provided, the tracks including servo sectors in which servo information is recorded, the servo sectors being arranged at intervals in a circumferential direction of the magnetic disk, the tracks including a first track and a second track, the second track being adjacent to the first track in a radial direction of the magnetic disk and being subjected to write before the first track;
• a magnetic head configured to write and read data to and from the magnetic disk;
• and
• a controller configured to
• calculate a weighting coefficient relative to each of multiple first positions located in the circumferential direction, the weighting coefficient being individually calculated for each of the multiple first positions based on quality of one or more of multiple second positions located in the circumferential direction, the one or more of the multiple second positions corresponding to the multiple first positions,
• start a write operation on the first track,
• execute a first operation when the magnetic head passes over each of the servo sectors during the write operation, the first operation being an operation of
• acquiring a squeeze amount that is a narrowed amount of a width of the second track from a design value caused by the write operation, the first operation being executed based on the servo information read every time the magnetic head passes over each of the servo sectors,
• multiplying the squeeze amount by the weighting coefficient,
• calculating a first amount obtained by accumulating an excess amount of the squeeze amount multiplied by the weighting coefficient over a first threshold for all second positions included in a range adjacent to a part in the circumferential direction where write by the write operation is completed among the second positions, and
• comparing the first amount with a second threshold, and
• perform interruption of the write operation and perform a protection operation of protecting data of the second track, based on a comparison result between the first amount and the second threshold.

A magnetic disk apparatus comprising:

• a magnetic disk on which tracks are provided, the tracks including servo sectors in which servo information is recorded, the servo sectors being arranged at intervals in a circumferential direction of the magnetic disk, each of the tracks including long-distance sectors, each of the long-distance sectors being a region in which data is written and being a region having a length in the circumferential direction over two or more servo sectors of the servo sectors, the tracks including a first track and a second track, the second track being adjacent to the first track in a radial direction of the magnetic disk and being subjected to write before the first track;
• a magnetic head configured to write and read data to and from the magnetic disk;
• and
• a controller configured to
• calculate a weighting coefficient individually for each of first long-distance sectors that are the long-distance sectors provided in the second track, the first threshold being calculated based on quality of each of the first long-distance sectors,
• in a write operation on a first part on the first track, the first part being a part adjacent to a second part, the second part being a part between two ends of a second long-distance sector in the circumferential direction, the second long-distance sector being one of the first long-distance sectors,
• calculate squeeze amounts at first positions in the circumferential direction included in the second long-distance sector based on the servo information read from one or more of the servo sectors where the magnetic head passes over among the two or more of the servo sectors included in the first part, the squeeze amounts each being a narrowed amount of a width of the second track from a design value caused by the write operation,
• multiply a total value of the squeeze amounts at the first positions by the weighting coefficient and compare the total value multiplied by the weighting coefficient with a first threshold relative to the second long-distance sector, and
• perform interruption of the write operation and perform a protection operation of protecting data of the second track, based on a comparison result between the total value multiplied by the weighting coefficient and the first threshold for the second long-distance sector.