Storage apparatus, method of controlling amount of write current overshoot in storage apparatus and storage medium storing its program
View Patent ↗A storage apparatus comprises: a current parameter varying section that can make a write current used for writing information on the storage medium and an overshoot amount corresponding to the write current variable; a detection section that detects an error rate or its corresponding error rate parameter for a plurality of combinations of the write current and overshoot amount varied by the current parameter varying section; a saturation factor calculation section that calculates a saturation factor representing a change in the error rate relative to a unit write current value from the error rate or error rate parameter detected by the detection section; and a current parameter setting section that determines current parameters based on the saturation factor obtained by the saturation factor calculation section for setting.
1. A storage apparatus that writes information on a storage medium using a write current, comprising:
a current parameter varying section that can make a write current used for writing information on the storage medium and an overshoot amount corresponding to the write current, variable;
a detection section that detects an error rate or an error rate parameter corresponding to the error rates for a plurality of combinations of the write current and the overshoot amount varied by the current parameter varying section;
a saturation factor calculation section that calculates a saturation factor representing a change in the error rate relative to a unit write current value from the error rate or the corresponding error rate parameter detected by the detection section; and
a current parameter setting section for setting current parameters based on the saturation factor obtained by the saturation factor calculation section.
2. The storage apparatus according to claim 1 , wherein
the detection section detects the error rate or the corresponding error rate parameter including side erase.
3. The storage apparatus according to claim 1 , further comprising a selection section that selects whether to allow the detection section to detect the error rate or the corresponding error rate parameter including side erase or to detect the error rate or the corresponding error rate parameter not including side erase.
4. The storage apparatus according to claim 1 , further comprising a current parameter setting control section that allows the detection section to detect a first error rate parameter not including side erase and allows the saturation factor calculation section to calculate a first saturation factor based on the first error rate parameter to thereby acquire current parameter candidates from the first saturation factor, and allows the detection section to detect a second error rate parameter including side erase with respect to the current parameter candidates, allows the saturation factor calculation section to calculate a second saturation factor based on the second error rate parameter, and allows the current parameter setting section to set the current parameters based on the second saturation factor.
5. The storage apparatus according to claim 1 , wherein
the detection section detects a VTM as the error rate parameter corresponding to the error rate.
6. The storage apparatus according to claim 1 , wherein
the saturation factor calculation section sets a plurality of zones for which the saturation factor is calculated based on a relationship between the write current and the error rate or the corresponding error rate parameter obtained by the detection section and calculates the saturation factor in respective zones, and
the current parameter setting section determines the current parameters based on a plurality of saturation factors obtained in the respective zones.
7. The storage apparatus according to claim 1 , wherein
the storage apparatus is a magnetic disk apparatus using a magnetic disk as the storage medium.
8. A method of controlling the amount of write current overshoot in a storage apparatus that writes information on a storage medium using a write current, comprising:
a write step that writes information on the storage medium while varying a write current and an overshoot amount corresponding to the write current;
a detection step that detects an error rate or an error rate parameter corresponding to the error rate for a plurality of combinations of the write current and the overshoot amount varied by the write step;
a saturation factor calculation step that calculates a saturation factor representing a change in the error rate relative to a unit write current value from the error rate or the corresponding error rate parameter detected by the detection step; and
a current parameter setting step for setting current parameters based on the saturation factor obtained by the saturation factor calculation step.
9. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , wherein
the detection step detects the error rate or the corresponding error rate parameter including side erase.
10. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , further comprising a selection step that selects whether to allow the detection step to detect the error rate or the corresponding error rate parameter including side erase or to detect the error rate or the corresponding error rate parameter not including side erase.
11. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , further comprising:
a current parameter candidate acquisition step that allows the detection step to detect a first error rate parameter not including side erase and allows the saturation factor calculation step to calculate a first saturation factor based on the first error rate parameter to thereby acquire current parameter candidates from the first saturation factor, wherein
the current parameter setting step allows the detection step to detect a second error rate parameter including side erase with respect to the current parameter candidates acquired by the current parameter candidate acquisition step, allows the saturation factor calculation step to calculate a second saturation factor based on the second error rate parameter to thereby set the current parameters based on the second saturation factor.
12. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , wherein the detection step detects a VTM as the error rate parameter corresponding to the error rate.
13. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , wherein
the saturation factor calculation step sets a plurality of zones for which the saturation factor is calculated based on a relationship between the write current and the error rate or the corresponding error rate parameter obtained by the detection step and calculates the saturation factor in respective zones, and
the current parameter setting step determines the current parameters based on a plurality of saturation factors obtained in the respective zones.
14. The method of controlling the amount of write current overshoot in a storage apparatus according to claim 8 , wherein
the storage apparatus is a magnetic disk apparatus using a magnetic disk as a storage medium.
15. As disk medium storing a write current overshoot amount control program that allows a computer to execute a method of controlling the amount of write current overshoot in a storage apparatus that writes information on a storage medium using a write current, the program allowing a computer to execute:
a write step that writes information on the storage medium while varying a write current and an overshoot amount corresponding to the write current;
a detection step that detects an error rate or an error rate parameter corresponding to the error rate for a plurality of combinations of the write current and the overshoot amount varied by the write step;
a saturation factor calculation step that calculates a saturation factor representing a change in the error rate relative to a unit write current value from the error rate or the corresponding error rate parameter detected by the detection step; and
a current parameter setting step for setting current parameters based on the saturation factor obtained by the saturation factor calculation step.
16. The disk medium according to claim 15 , wherein
the detection step detects the error rate or the corresponding error rate parameter including side erase.
17. The disk medium according to claim 15 , further comprising a selection step that selects whether to allow the detection step to detect the error rate or the corresponding error rate parameter including side erase or to detect the error rate or the corresponding error rate parameter not including side erase.
18. The disk medium according to claim 15 , further comprising:
a current parameter candidate acquisition step that allows the detection step to detect a first error rate parameter not including side erase and allows the saturation factor calculation step to calculate a first saturation factor based on the first error rate parameter to thereby acquire current parameter candidates from the first saturation factor, wherein
the current parameter setting step allows the detection step to detect a second error rate parameter including side erase with respect to the current parameter candidates acquired by the current parameter candidate acquisition step, allows the saturation factor calculation step to calculate a second saturation factor based on the second error rate parameter to thereby set the current parameters based on the second saturation factor.
19. The disk medium according to claim 15 , wherein
the detection step detects a VTM as the error rate parameter corresponding to the error rate.
20. The disk medium according to claim 15 , wherein
the saturation factor calculation step sets a plurality of zones for which the saturation factor is calculated based on a relationship between the write current and the error rate or the corresponding error rate parameter obtained by the detection step and calculates the saturation factor in respective zones, and
the current parameter setting step determines the current parameters based on a plurality of saturation factors obtained in the respective zones.