Behavioral model for dynamic tension compensation

• US 10,276,204 B1
• Filed: 04/24/2018
• Issued: 04/30/2019
• Est. Priority Date: 04/24/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Judd, Kevin B., Gale, Ernest S., Inch, Randy C., Ogura, Eiji, Tsuruta, Kazuhiro, Nylander-Hill, Pamela R., Miyamura, Tsuyoshi
• Primary Examiner(s): Hindi, Nabil Z
• Application Number:
  US15/961,682
• Time in Patent Office: 371 Days
• Field of Search: 360 31, 360 53, 360 70, 360 723, 360 7304, 360 7312, 360 743, 360 7802
• CPC Class Codes: G11B 15/43 Control or regulation of mechanical tension of record carrier, e.g. tape tension
• CPC Class Codes: G11B 2020/183 wherein at least one additional attempt is made to read or write the data when a first attempt is unsuccessful
• CPC Class Codes: G11B 27/36 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 Class Codes: G11B 5/5539 Skew adjustment, e.g. adjustment of the position of the first sector in each track with respect to the other tracks, for improving, e.g. access performance
• CPC Class Codes: G11B 5/70642 iron oxides

Abstract

A tape drive-implemented method, according to one embodiment, includes: detecting a read error, determining whether a current tension setting of the magnetic tape is accurate, determining whether the read error is part of an error burst in response to determining that the current tension setting of the magnetic tape is accurate, sending instructions to perform a first re-read attempt in response to determining that the read error is not part of an error burst, determining whether the first re-read attempt was performed successfully, selecting a range of tension settings in response to determining that the first re-read attempt was not performed successfully, selecting a range of lateral offsets, sending instructions to apply each unique combination of tension settings and lateral offsets, for each of the unique combinations applied, sending instructions to perform a second phase re-read attempt, and determining whether the second phase re-read attempt was performed successfully.

Claims

1. A tape drive-implemented method, comprising:

initiating performance of a read request on a magnetic tape;

detecting a read error;

examining performance data corresponding to portions of the read request which have been performed;

determining whether a current tension setting of the magnetic tape is accurate;

determining whether the read error is part of an error burst in response to determining that the current tension setting of the magnetic tape is accurate;

sending one or more instructions to perform a first re-read attempt on a portion of the magnetic tape corresponding to the read error in response to determining that the read error is not part of an error burst;

determining whether the first re-read attempt was performed successfully;

selecting a range of tension settings in response to determining that the first re-read attempt was not performed successfully;

selecting a range of lateral offsets;

sending one or more instructions to apply each unique combination of a tension setting from the range of tension settings and a lateral offset from the range of lateral offsets;

for each of the unique combinations applied, sending one or more instructions to perform a second phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determining whether the second phase re-read attempt was performed successfully for any of the unique combinations.

2. The tape-drive implemented method as recited in claim 1, comprising:

sending one or more instructions to revert a channel calibration to a nominal value in response to determining that the second phase re-read attempt was not performed successfully for any of the unique combinations;

sending one or more instructions to apply one or more setting changes;

sending one or more instructions to perform a third phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determining that a permanent error exists on the magnetic tape in response to determining that the third re-read attempt was not performed successfully.

3. The tape-drive implemented method as recited in claim 2, wherein the one or more setting changes correspond to settings which are selected from a group of settings consisting of:

dataflow, channel calibration, servo orientation, and magnetic tape speed.

4. The tape-drive implemented method as recited in claim 2, comprising:

prior to sending the one or more instructions to perform the third phase re-read attempt, sending one or more instructions to perform a rechuck of the magnetic tape.

5. The tape-drive implemented method as recited in claim 1, comprising:

using at least a portion of the performance data to determine an updated tension setting in response to determining that the read error is part of an error burst; and

sending one or more instructions to seed the updated tension setting, thereby adjusting the current tension setting.

6. The tape-drive implemented method as recited in claim 1, comprising:

using table to determine an updated tension setting in response to determining that the read error is part of an error burst; and

sending one or more instructions to force the updated tension setting, thereby adjusting the current tension setting.

7. The tape-drive implemented method as recited in claim 1, wherein the performance data is selected from a group consisting of:

data channel performance, tension error criteria, data correction status information, error history information, persistent settings, and initial conditions.

8. The tape-drive implemented method as recited in claim 1, wherein the range of tension settings are selected based on a portion of the magnetic tape at which the read error occurred.

9. A computer program product comprising a computer readable storage medium having program instructions embodied therewith, wherein the computer readable storage medium is not a transitory signal per se, the program instructions readable and/or executable by a processor to cause the processor to perform a method comprising:

initiating, by the processor, performance of a read request on a magnetic tape;

detecting, by the processor, a read error;

examining, by the processor, performance data corresponding to portions of the read request which have been performed;

determining, by the processor, whether a current tension setting of the magnetic tape is accurate;

determining, by the processor, whether the read error is part of an error burst in response to determining that the current tension setting of the magnetic tape is accurate;

sending, by the processor, one or more instructions to perform a first re-read attempt on a portion of the magnetic tape corresponding to the read error in response to determining that the read error is not part of an error burst;

determining, by the processor, whether the first re-read attempt was performed successfully;

selecting, by the processor, a range of tension settings in response to determining that the first re-read attempt was not performed successfully;

selecting, by the processor, a range of lateral offsets;

sending, by the processor, one or more instructions to apply each unique combination of a tension setting from the range of tension settings and a lateral offset from the range of lateral offsets;

for each of the unique combinations applied, sending, by the processor, one or more instructions to perform a second phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determining, by the processor, whether the second phase re-read attempt was performed successfully for any of the unique combinations.

10. The computer program product as recited in claim 9, the program instructions readable and/or executable by the processor to cause the processor to perform the method comprising:

sending, by the processor, one or more instructions to revert a channel calibration to a nominal value in response to determining that the second phase re-read attempt was not performed successfully for any of the unique combinations;

sending, by the processor, one or more instructions to apply one or more setting changes;

sending, by the processor, one or more instructions to perform a third phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determining, by the processor, that a permanent error exists on the magnetic tape in response to determining that the third phase re-read attempt was not performed successfully.

11. The computer program product as recited in claim 10, wherein the one or more setting changes correspond to settings which are selected from a group of settings consisting of:

dataflow, channel calibration, servo orientation, and magnetic tape speed.

12. The computer program product as recited in claim 10, the program instructions readable and/or executable by the processor to cause the processor to perform the method comprising:

prior to sending the one or more instructions to perform the third phase re-read attempt, sending, by the processor, one or more instructions to perform a rechuck of the magnetic tape.

13. The computer program product as recited in claim 9, the program instructions readable and/or executable by the processor to cause the processor to perform the method comprising:

using, by the processor, at least a portion of the performance data to determine an updated tension setting in response to determining that the read error is part of an error burst; and

sending, by the processor, one or more instructions to seed the updated tension setting, thereby adjusting the current tension setting.

14. The computer program product as recited in claim 9, the program instructions readable and/or executable by the processor to cause the processor to perform the method comprising:

using, by the processor, table to determine an updated tension setting in response to determining that the read error is part of an error burst; and

sending, by the processor, one or more instructions to force the updated tension setting, thereby adjusting the current tension setting.

15. The computer program product as recited in claim 9, wherein the performance data is selected from a group consisting of:

data channel performance, tension error criteria, data correction status information, error history information, persistent settings, and initial conditions.

16. The computer program product as recited in claim 9, wherein the range of tension settings are selected based on a portion of the magnetic tape at which the read error occurred.

17. A system, comprising:

a processor; and

logic integrated with and/or executable by the processor, the logic being configured to cause the processor to;

initiate, by the processor, performance of a read request on a magnetic tape;

detect, by the processor, a read error;

examine, by the processor, performance data corresponding to portions of the read request which have been performed;

determine, by the processor, whether a current tension setting of the magnetic tape is accurate;

determine, by the processor, whether the read error is part of an error burst in response to determining that the current tension setting of the magnetic tape is accurate;

send, by the processor, one or more instructions to perform a first re-read attempt on a portion of the magnetic tape corresponding to the read error in response to determining that the read error is not part of an error burst;

determine, by the processor, whether the first re-read attempt was performed successfully;

select, by the processor, a range of tension settings in response to determining that the first re-read attempt was not performed successfully;

select, by the processor, a range of lateral offsets;

send, by the processor, one or more instructions to apply each unique combination of a tension setting from the range of tension settings and a lateral offset from the range of lateral offsets;

for each of the unique combinations applied, send, by the processor, one or more instructions to perform a second phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determine, by the processor, whether the second phase re-read attempt was performed successfully for any of the unique combinations.

18. The system as recited in claim 17, the logic being configured to cause the processor to:

send, by the processor, one or more instructions to revert a channel calibration to a nominal value in response to determining that the second re-read attempt was not performed successfully for any of the unique combinations;

send, by the processor, one or more instructions to apply one or more setting changes;

send, by the processor, one or more instructions to perform a third phase re-read attempt on the portion of the magnetic tape corresponding to the read error; and

determine, by the processor, that a permanent error exists on the magnetic tape in response to determining that the third re-read attempt was not performed successfully.

19. The system as recited in claim 18, wherein the one or more setting changes correspond to settings which are selected from a group of settings consisting of:

dataflow, channel calibration, servo orientation, and magnetic tape speed.

20. The system as recited in claim 18, the logic being configured to cause the processor to:

prior to sending the one or more instructions to perform the third phase re-read attempt, send, by the processor, one or more instructions to perform a rechuck of the magnetic tape.

21. The system as recited in claim 17, the logic being configured to cause the processor to:

use, by the processor, at least a portion of the performance data to determine an updated tension setting in response to determining that the read error is part of an error burst; and

send, by the processor, one or more instructions to seed the updated tension setting, thereby adjusting the current tension setting.

22. The system as recited in claim 17, the logic being configured to cause the processor to:

use, by the processor, table to determine an updated tension setting in response to determining that the read error is part of an error burst; and

send, by the processor, one or more instructions to force the updated tension setting, thereby adjusting the current tension setting.

23. The system as recited in claim 17, wherein the performance data is selected from a group consisting of:

data channel performance, tension error criteria, data correction status information, error history information, persistent settings, and initial conditions.

24. The system as recited in claim 17, wherein the range of tension settings are selected based on a portion of the magnetic tape at which the read error occurred.

25. A tape drive-implemented method, comprising:

sending one or more instructions to initiate performance of a read request on a magnetic tape;

detecting a read error;

examining performance data corresponding to portions of the read request which have been performed;

determining whether a current tension setting of the magnetic tape is accurate;

sending one or more instructions to remove the current tension setting in response to determining that the current tension setting of the magnetic tape is not accurate;

determining whether the read error is part of an error burst;

using historical data and read correction data to determine whether to adjust the current tension setting in response to determining that the read error is part of an error burst, wherein using the historical data and the read correction data includes;

counting a number of channels that are unreadable; and

assessing whether the unreadable channels have an overall channel degradation pattern which affects channels which are located closer to an edge of the magnetic tape more than channels which are located closer to a longitudinal axis of the magnetic tape;

sending one or more instructions to perform a first re-read attempt on a portion of the magnetic tape corresponding to the read error in response to determining that the error is not part of an error burst on the magnetic tape;

determining whether the first re-read attempt was performed successfully;

selecting a range of tension settings from a tension table in response to determining that the first re-read attempt was not performed successfully, wherein the tension table includes multiple ranges of tension settings, wherein each range of tension settings includes a sequence of tension settings that incorporates a nominal tension setting;

selecting a range of position error signal (PES) lateral offsets from PES table, wherein the PES table includes multiple ranges of PES lateral offset settings;

sending one or more instructions to apply each PES lateral offset in the selected range of PES lateral offsets with each tension setting in the selected range of tension settings;

sending one or more instructions to perform an additional re-read attempt for each unique combination of a PES lateral offset and a tension setting applied;

determining whether any of the additional re-read attempts were performed successfully;

sending one or more instructions to apply one or more calibration changes in response to determining that none of the additional re-read attempts were performed successfully;

sending one or more instructions to apply dataset reconstruction and iterative decode operations;

sending one or more instructions to perform a third phase re-read attempt;

determining whether the third phase re-read attempt was performed successfully; and

concluding that a permanent error exists on the magnetic tape in response to determining that the third re-read attempt was not performed successfully.