Magnetic disk device and information management method

1. A magnetic disk device comprising:

a first disk having a first user data region to which user data is written and a first system area different from the first user data region;

a second disk having a second user data region to which user data is written and a second system area different from the second user data region;

a first head configured to write data to the first disk and read data from the first disk;

a second head configured to write data to the second disk and read data from the second disk;

a first actuator configured to move the first head;

a second actuator configured to move the second head;

a first controller configured to control the first disk, the first head, and the first actuator; and

a second controller configured to control the second disk, the second head, and the second actuator, wherein

the second controller controls the second head to record first information related to the first head and the first disk, in the second system area.

2. The magnetic disk device according to claim 1 , wherein the first controller controls the first head to record the first information in the first system area.

3. The magnetic disk device according to claim 2 , further comprising:

a volatile memory, wherein

the first controller records the first information in the volatile memory.

4. The magnetic disk device according to claim 3 ,

wherein periodically, the first controller controls the first head to record the first information recorded in the volatile memory, in the first system area, or the second controller controls the second head to record the first information recorded in the volatile memory, in the second system area,

wherein the first information recorded in the volatile memory and periodically recorded in the first or second system area is updated, and

wherein a time-stamp is added to the updated first information.

5. The magnetic disk device according to claim 4 ,

wherein when a number of commands to be processed by the first controller is large, and when a number of commands to be processed by the second controller is small, the second controller controls the second head to record the first information recorded in the volatile memory, in the second system area,

wherein the first information recorded in the volatile memory and in the second system area is, and

wherein a time-stamp is added to the updated first information recorded in the volatile memory and in the second system area.

6. The magnetic disk device according to claim 5 ,

wherein when the number of commands to be processed by the first controller is small, the first controller controls the first head to record the first information recorded in the volatile memory, in the first system area,

wherein the first information recorded in the volatile memory and in the first system area is updated, and

wherein a time-stamp is added to the updated first information recorded in the volatile memory and in the first system area.

7. The magnetic disk device according to claim 6 , wherein at startup, the first controller records the first information having a larger time-stamp among the first information recorded in the first system area and the first information recorded in the second system area, in the volatile memory.

8. The magnetic disk device according to claim 1 , wherein the first information corresponds to a table showing a degree of influence of a leakage magnetic flux according to a number of times data is written to a region adjacent to the first disk in a radial direction.

9. The magnetic disk device according to claim 1 , wherein the first controller controls the first head to record second information related to the second head and the second disk, in the first system area.

10. The magnetic disk device according to claim 9 , wherein the second controller records the second information in a volatile memory.

11. The magnetic disk device according to claim 10 ,

wherein periodically, the first controller controls the first head to record the second information recorded in the volatile memory, in the first system area, or the second controller controls the second head to record the second information recorded in the volatile memory, in the second system area,

wherein the second information recorded in the volatile memory and periodically recorded in the first or second system area is updated, and

wherein a time-stamp is added to the updated second information.

12. The magnetic disk device according to claim 11 ,

wherein when a number of commands to be processed by the second controller is large, and when a number of commands to be processed by the first controller is small, the first controller controls the first head to record the second information recorded in the volatile memory, in the first system area,

wherein the second information recorded in the volatile memory and in the first system area is updated, and

wherein a time-stamp is added to the updated second information recorded in the volatile memory and in the first system area.

13. The magnetic disk device according to claim 12 ,

wherein when the number of commands to be processed by the second controller is small, the second controller controls the second head to record the second information recorded in the volatile memory, in the second system area,

wherein the second information recorded in the volatile memory and in the second system area is updated, and

wherein a time-stamp is added to the second information recorded in the volatile memory and in the second system area.

14. The magnetic disk device according to claim 13 , wherein at startup, the second controller records the second information having a larger time-stamp among the second information recorded in the first system area and the second information recorded in the second system area, in the volatile memory.

15. The magnetic disk device according to claim 9 , wherein the second information corresponds to a table showing a degree of influence of a leakage magnetic flux according to a number of times data is written to a region adjacent to the second disk in a radial direction.

16. A magnetic disk device comprising:

a volatile memory;

a plurality of disks including a first disk and a second disk, each having a user data region to which user data is written and a system area different from the user data region;

a plurality of heads including a first head facing the first disk and a second head, configured to write data to respective disks and read data from the respective disks;

a plurality of actuators configured to move respective heads; and

a plurality of controllers including a first controller and a second controller, configured to control the disks, the heads, and the actuators, wherein

the second controller controls the second head to record first information related to the first head, the system area of the second disk.

17. The magnetic disk device according to claim 16 , wherein the first controller controls the first head to record the first information in the system area of the first disk and records the first information in the volatile memory.

18. The magnetic disk device according to claim 17 ,

wherein periodically, one of the plurality of controllers controls one of the plurality of heads to record the first information recorded in the volatile memory, in the system area of one of the plurality of disks,

wherein the first information recorded in the volatile memory and periodically recorded in the system area of the one of the plurality of disks is updated, and

wherein a time-stamp is added to the updated first information.

19. An information management method applied to a magnetic disk device including a volatile memory, a plurality of disks including a first disk and a second disk, each having a user data region to which user data is written and a system area different from the user data region, a plurality of heads including a first head facing the first disk and a second head, configured to write data to respective disks and read data from the respective disks, a plurality of actuators configured to move respective heads, and a plurality of controllers including a first controller and a second controller, configured to control the disks, the heads, and the actuators, the method comprising:

by the second controller, controlling the second head to record first information related to the first head, in the system area of the second disk.

20. The information management method according to claim 19 , further comprising:

by the first controller, controlling the first head to record the first information in the system area of the first disk and record the first information in the volatile memory; and

periodically, by one of the plurality of controllers, controlling one of the plurality of heads, to record the first information, which is updated with the volatile memory and to which a time-stamp is added, in the system area of one of the plurality of disks.