Magnetic disk device and recording method

Patent metadata

Field	Value
Publication number	US-10607643-B2
Application number	US-201816120292-A
Country	US
Kind code	B2
Filing date	Sep 2, 2018
Priority date	Mar 16, 2018
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

A magnetic disk device includes a magnetic head that writes data on and reads data from the magnetic disk, and a controller circuit. The controller circuit is configured to control a gap between the magnetic head and the magnetic disk, and select one of two or more gap values for the fly height, based on a write location in the magnetic disk of data to be written by the magnetic head.

First claim

What is claimed is:

1. A magnetic disk device comprising:
a magnetic disk;
a magnetic head that writes data on and reads data from the magnetic disk; and
a controller circuit configured to:
control a gap between the magnetic head and the magnetic disk,
select a first gap value for the gap when a write location in the magnetic disk of data to be written by the magnetic head is a user data recording area,
count a number of times that the data written to the write location has been read, and
when the number of times that the data written to the write location has been read reaches a specified value, rewrite the data written to the write location to a surplus area of the magnetic disk with the gap set at a second gap value that is greater than the first gap value.

2. The magnetic disk device according to claim 1 ,
wherein the control circuit is further configured to select the second gap value for the gap when the write location of the data is a system area.

3. The magnetic disk device according to claim 2 ,
wherein a difference between the first gap value and the second gap value is equal to or greater than 15 nm.

4. The magnetic disk device according to claim 2 ,
wherein, when the second gap value for the gap is selected, the controller circuit increases a current during writing by the magnetic head.

5. The magnetic disk device according to claim 2 ,
wherein the controller circuit is configured to, after data has been written to the write location, verify whether or not the data written to the write location has been written correctly.

6. The magnetic disk device according to claim 1 , wherein the controller circuit is further configured to count the number of times within a predetermined time after the data have been written to the write location.

7. The magnetic disk device according to claim 1 ,
wherein when the number of times reaches the specified value, the controller circuit:
determines whether or not the recorded data written to the write location can be rewritten to the surplus area, and
outputs a notification when the surplus area has insufficient capacity to store the data written to the write location.

8. The magnetic disk device according to claim 2 ,
wherein, when the second gap value for the gap is selected, the controller circuit decreases at least one of a bytes per inch (BPI) and a tracks per inch (TPI) of the data while writing the data to the write location by the magnetic head.

9. The magnetic disk device according to claim 2 ,
wherein the first gap value and the second gap value are selected so that a maximum recording density of the system area is less than or equal to a maximum recording density of the user data recording area minus a recording density associated with a targeted bit error rate for the disk device times a difference between the second gap value and the first gap value.

10. The magnetic disk device according to claim 9 ,
wherein the recording density associated with the targeted bit error rate has a value between about 100 kilobytes per inch and about 300 kilobytes per inch.

11. A method of storing data in a magnetic disk device that includes a magnetic head that writes data to and reads data from a magnetic disk, the method comprising:
selecting a first gap value for a gap between the magnetic head and the magnetic disk when a write location in the magnetic disk of data to be written by the magnetic head is a user data recording area;
controlling the gap of the magnetic head from the magnetic disk at the selected gap value;
counting a number of times that the data written to the write location has been read; and
when the number of times that the data written to the write location has been read reaches a specified value, rewriting the data written to the write location to a surplus area of the magnetic disk with the gap set at a second gap value that is greater than the first gap value.

12. The method according to claim 11 , further comprising:
selecting the second gap value for the gap when the write location of the data is a system area.

13. The method according to claim 11 ,
wherein a difference between the first gap value and the second gap value is equal to or greater than 15 nm.

14. The method according to claim 12 ,
further comprising, when the second gap value for the gap is selected, increasing a current during writing by the magnetic head.

15. The method according to claim 11 ,
further comprising, after the data has been written to the write location, verifying whether or not the data written to the write location has been written correctly.

16. The method according to claim 11 , further comprising:
counting the number of times within a predetermined time after the data have been written to the write location.

17. The method according to claim 11 , further comprising:
when the number of times reaches the specified value, determining whether or not the recorded data written to the write location can be rewritten to the surplus area, and outputting a notification when the surplus area has insufficient capacity to store the data written to the write location.

18. The method according to claim 12 , further comprising:
when the second gap value for the gap is selected, decreasing at least one of a bytes per inch (BPI) and a tracks per inch (TPI) of the data while writing the data to the write location by the magnetic head.

Assignees

• Toshiba Kk
• Toshiba Electronic Devices & Storage Corp

Inventors

• Aoyagi Yuka

Classifications

• G11B5/58 Primary

  with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following {(spacing means incorporated in the head structure G11B5/187, G11B5/255, G11B5/3106)} · CPC title

• G11B5/012

  Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence) · CPC title

• G11B5/4886

  relative to rotating disc · CPC title

• G11B5/6064

  using air pressure · CPC title

• G11B5/607 Primary

  using thermal means · CPC title