Control device and storage device

1. A control device that controls a storage device having an auto-gain-control function for controlling strength of an output signal from a head that reads data from a storage medium, the control device comprising:

a determining unit that determines whether the strength of the output signal controlled by the auto-gain-control function is within a predetermined range;

a detecting unit that detects an abnormal float of the head based on a determination made by the determining unit;

a counting unit that counts a number of times the detecting unit detects abnormal float of the head; and

a storing unit that stores the number of times of the abnormal floats counted by the counting unit into a storage area of the storage device.

2. The control device according to claim 1 , wherein the detecting unit detects the abnormal float of the head for each of zones on the storage medium.

3. The control device according to claim 1 , wherein the detecting unit detects the abnormal float of the head with respect to each predetermined time-period-section and records a plurality of pieces of data of each detection status corresponding to each time-period-section.

4. The control device according to claim 1 , wherein the detecting unit detects the abnormal float of the head at all times.

5. The control device according to claim 1 , wherein the detecting unit detects the abnormal float of the head regularly.

6. The control device according to claim 1 , further comprising:

a shock detecting unit that detects a shock applied to the storage device from an external source; and

a shock-number counting unit that counts a number of times the shock detecting unit detects shock to the storage device, wherein

the storing unit stores a value obtained by subtracting the number of times of the shocks counted by the shock-number counting unit from the number of times of the abnormal floats counted by the counting unit into the storage area.

7. The control device according to claim 1 , further comprising a failure determining unit that determines a possibility of an occurrence of a failure of the head based on the number of times of the abnormal floats of the head counted by the counting unit.

8. The control device according to claim 7 , wherein the failure determining unit determines the possibility of an occurrence of a failure based on data of detection of the abnormal floats of the head recorded in a chronological sequence.

9. The control device according to claim 7 , further comprising an alert sending unit that sends an alert to a higher-level device when the failure determining unit determines that there is a possibility of an occurrence of a failure of the head.

10. A storage device having an auto-gain-control function for controlling strength of an output signal from a head that reads data from a storage medium, the storage device comprising:

a determining unit that determines whether the strength of the output signal controlled by the auto-gain-control function is within a predetermined range;

a detecting unit that detects an abnormal float of the head based on determination made by the determining unit;

a counting unit that counts a number of times the detecting unit detects abnormal float of the head; and

a storing unit that stores therein the number of times of the abnormal floats counted by the counting unit into a storage area of the storage device.

11. The storage device according to claim 10 , wherein the detecting unit detects the abnormal float of the head for each of zones on the storage medium.

12. The storage device according to claim 10 , wherein the detecting unit detects the abnormal float of the head with respect to each predetermined time-period-section and records a plurality of pieces of data of each detection status corresponding to each time-period-section.

13. The storage device according to claim 10 , wherein the detecting unit detects the abnormal float of the head at all times.

14. The storage device according to claim 10 , wherein the detecting unit detects the abnormal float of the head regularly.

15. The storage device according to claim 10 , further comprising:

a shock detecting unit that detects a shock applied to the storage device from an external source; and

a shock-number counting unit that counts a number of times the shock detecting unit detects shock to the storage device, wherein

the storing unit stores a value obtained by subtracting the number of times of the shocks counted by the shock-number counting unit from the number of times of the abnormal floats counted by the counting unit of the storage area.

16. The storage device according to claim 10 , further comprising a failure determining unit that determines a possibility of an occurrence of a failure of the head based on the number of times of the abnormal floats of the head counted by the counting unit.

17. The storage device according to claim 16 , wherein the failure determining unit determines the possibility of an occurrence of a failure based on data of detection of the abnormal floats of the head recorded in a chronological sequence.

18. The storage device according to claim 16 , further comprising an alert sending unit that sends an alert to a higher-level device when the failure determining unit determines that there is a possibility of an occurrence of a failure of the head.

19. A control method for controlling a storage device having an auto-gain-control function for controlling strength of an output signal from a head that reads data from a storage medium, the control method comprising:

determining whether the strength of the output signal controlled by the auto-gain-control function is within a predetermined range;

detecting an abnormal float of the head based on a determination made at the determining;

counting a number of times of the abnormal floats of the head detected at the detecting; and

storing the number of times of the abnormal floats counted at the counting into a storage area of the storage device.