Dynamically optimizing read performance by adjusting servo-based head location

Patent metadata

Field	Value
Publication number	US-2016019919-A1
Application number	US-201414332277-A
Country	US
Kind code	A1
Filing date	Jul 15, 2014
Priority date	Jul 15, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

In one embodiment, a method includes determining a reading performance based on one or more metrics, adjusting a commanded lateral reading location of a head relative to a medium, determining the reading performance after the adjusting, comparing the reading performance after the adjusting relative to the reading performance before the adjusting for determining whether the reading performance has improved, and selecting a commanded lateral reading location based on the comparing. In another embodiment, a controller is configured to perform the foregoing method. In yet another embodiment, a computer program product includes a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a controller configured to perform the foregoing method.

First claim

1 . A computer-implemented method, comprising:
determining a reading performance of a head positioned at a commanded lateral reading location based on one or more metrics; adjusting a lateral reading location of the head relative to a medium by moving the head in a lateral direction away from the commanded lateral reading location to an adjusted lateral reading location; determining a reading (performance of the head after the adjusting; comparing the reading performance after the adjusting to the reading performance before the adjusting for determining whether the reading performance has improved; and selecting an optimal lateral reading location based on the comparing; wherein the adjusted lateral reading location corresponds to a new lateral servo location relative to a previous lateral servo location used prior to the adjusting; and wherein the new lateral servo location and the previous lateral servo location are spatially separated by a predefined adjustment increment in an analog domain.

2 . The method of claim 1 , in response to determining the reading performance has improved after the adjusting, performing at least one of:
maintaining the adjusted lateral reading location, and adjusting the lateral reading location of the head by moving the head away from the adjusted lateral reading location in the lateral direction and comparing a resulting reading performance with a previous reading performance.

3 . The method of claim 1 , comprising, in response to determining the reading performance has not improved after the adjusting,
adjusting the lateral reading location of the head by moving the head away from the commanded lateral reading location in a different lateral direction and comparing a resulting reading performance with a previous reading performance.

4 . The method of claim 1 , wherein the determining, the comparing and the adjusting are performed in response to detecting a trigger condition comprising at least two of a logical input, a user input, and end of a timer sequence, a system humidity warning, and a system temperature warning.

5 . The method of claim 1 , wherein the determining, the adjusting and the comparing are performed continuously while the head is actively engaged in a read operation.

6 . The method of claim 1 , wherein the one or more metrics are selected from a group consisting of C1 error correction rate, and C2 error correction rate.

7 . The method of claim 1 , wherein the reading performance is determined using information from multiple read channels configured to operate simultaneously,
wherein when the reading performance has improved after the adjusting, at least one of:
maintaining the adjusted lateral reading location, and
adjusting the adjusted lateral reading location by moving the head away from the adjusted lateral reading location in the lateral direction and comparing a resulting reading performance with a previous reading performance,
wherein when the reading performance has not improved after the adjusting, at least one of:
maintaining the adjusted lateral reading location,
restoring the head to the commanded lateral reading location; and
adjusting the adjusted lateral reading location by moving the head away from the commanded lateral reading location in a different lateral direction and comparing a resulting reading performance with a previous reading performance, and
wherein the one or more metrics are selected from a group consisting of C1 error correction rate, C2 error correction rate, mean square error rate, and output from a maximum likelihood detector.

8 . An apparatus, comprising:
a controller and logic integrated with and/or executable by the controller to: determine a reading performance of a head positioned at a commanded lateral reading location based on one or more metrics; adjust a lateral reading location of the head relative to a medium by instructing the head to move in a lateral direction away from the commanded lateral reading location in to an adjusted lateral reading location; determine the reading performance of the head after the adjustment; compare the reading performance after adjustment to the reading performance before adjustment for determining whether the reading performance has improved; and select an optimal lateral reading location based on the comparing, wherein the commanded lateral reading location and the adjusted lateral reading location are spatially separated by a predefined adjustment increment in an analog domain.

9 . An apparatus as recited in claim 8 , further comprising logic integrated with and/or executable by the controller to determine whether the reading performance has improved after adjustment, and in response to determining the reading performance has improved, either:
maintain the adjusted lateral reading location, or adjust the lateral reading location of the head in a same direction and comparing a resulting reading performance with a previous reading performance.

10 . An apparatus as recited in claim 8 , further comprising logic integrated with and/or executable by the controller to:
determine whether the reading performance has improved after adjustment, and in response to determining the reading performance has not improved adjusting the lateral reading location of the head by moving the head away from the commanded lateral reading location in a different direction and comparing a resulting reading performance with a previous reading performance.

11 . An apparatus as recited in claim 8 , wherein the one or more metrics comprise one or more benchmark values captured during one or more write operations.

12 . An apparatus as recited in claim 8 , wherein the determining, the adjusting, the comparing and the selecting are performed continuously while the head is actively engaged in a read operation.

13 . An apparatus as recited in claim 8 , wherein the one or more metrics are selected from a group consisting of C1 error correction rate, and C2 error correction rate.

14 . An apparatus as recited in claim 8 , wherein the reading performance is determined using information from multiple read channels configured to operate simultaneously.

15 . An apparatus as recited in claim 8 , further comprising:
the head, wherein the head is electrically coupled to the controller; an actuator mechanism for actuating the head in the analog domain; and a drive mechanism for passing a magnetic medium over the head.

16 . A computer program product, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a controller to cause the controller to:
determine, by the controller, a reading performance of a head positioned at a commanded lateral reading location based on one or more metrics; adjust, by the controller, a lateral reading location of the head relative to a medium by instructing the head to move in a lateral direction away from the commanded lateral reading location to an adjusted lateral reading location; determine, by the controller, a reading performance of the head after the adjusting; compare, by the controller, the reading performance after the adjusting to the reading performance before the adjusting for determining whether the reading performance has improved; and select, by the controller, an optimal lateral reading location based on the comparing, wherein the one or more metrics comprise one or more benchmark values captured during one or more write operations.

17 . The computer program p

Assignees

• IBM

Inventors

• Gale Ernest S
• Inch Randy C
• Judd Kevin B
• Swanson David L

Classifications

• G11B2220/956

  Linear tape open [LTO] format · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G11B5/012

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

• G11B5/584 Primary

  for track following on tapes · CPC title

• G11B27/36

  Monitoring, i.e. supervising the progress of recording or reproducing {(for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06)} · CPC title