Microcode data recovery strategies for use of iterative decode

• US 9,621,193 B1
• Filed: 01/05/2016
• Issued: 04/11/2017
• Est. Priority Date: 01/05/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bentley, Steven R., Nylander-Hill, Pamela R.
• Primary Examiner(s): Alphonse, Fritz
• Application Number:
  US14/987,921
• Time in Patent Office: 462 Days
• Field of Search: 714771, 714755, 714784, 714763, 714 56
• CPC Class Codes: G06F 11/10 Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/2909 Product codes
• CPC Class Codes: H03M 13/2927 Decoding strategies
• CPC Class Codes: H03M 13/293 with erasure setting
• CPC Class Codes: H03M 13/3746 with iterative decoding
• CPC Class Codes: H03M 13/3761 using code combining, i.e. using combining of codeword portions which may have been transmitted separately, e.g. Digital Fountain codes, Raptor codes or Luby Transform [LT] codes
• CPC Class Codes: H03M 13/611 Specific encoding aspects, e.g. encoding by means of decoding

Abstract

Various embodiments for data error recovery in a tape storage system, by a processor device, are provided. In one embodiment, a method comprises, in a tape storage system using an iterative hardware decoder, dynamically initializing at least one microcode-initiated decode cycle on a buffered dataset, each iterative decode cycle providing an error feedback loop.

Claims

1. A method for data error recovery in a tape storage system, by a processor device, comprising:

in a tape storage system using an iterative hardware decoder, dynamically initializing at least one microcode iterative decode cycle on a buffered dataset, each iterative decode cycle providing an error feedback loop;

initiating n microcode iterative decode cycles on the buffered dataset while tape is at speed;

wherein n comprises a number of microcode iterative decode cycles able to complete without stopping the tape due to buffering; and

initiating x microcode iterative decode cycles on the buffered dataset while the tape is stopped;

wherein x comprises at least one of a plurality of the microcode iterative decode cycles.

2. The method of claim 1, further including initializing the at least one microcode iterative decode cycle on the buffered dataset when an uncorrectable read error occurs.

3. The method of claim 1, wherein providing an error feedback loop comprises, for a next microcode iterative decode cycle, building upon data corrections obtained in a previous microcode iterative decode cycle.

4. The method of claim 1, further including initiating the x microcode iterative decode cycles on the buffered dataset until a predetermined error correction threshold is reached.

5. The method of claim 4, further including, upon reaching the predetermined error correction threshold, rereading data of the buffered dataset from the tape following a backhitch reposition.

6. The method of claim 5, further including, upon rereading the data of the buffered dataset from the tape, changing at least one of a plurality of read configuration characteristics.

7. The method of claim 6, further including monitoring and tracking at least one of a sub-dataset uncorrectable error status (UE) and an accumulated correction count (CORCNT) of attempted error corrections.

8. The method of claim 1, further including maintaining at least one of a log counter and a tape map histogram of successful and unsuccessful attempts of the at least one microcode iterative decode cycle.

9. A system for data error recovery in a tape storage system, comprising:

at least one processor device, wherein the at least one processor device;

in a tape storage system using an iterative hardware decoder, dynamically initializes at least one microcode iterative decode cycle on a buffered dataset, each iterative decode cycle providing an error feedback loop,

initiates n microcode iterative decode cycles on the buffered dataset while tape is at speed;

wherein n comprises a number of microcode iterative decode cycles able to complete without stopping the tape due to buffering, and

initiates x microcode iterative decode cycles on the buffered dataset while the tape is stopped;

wherein x comprises at least one of a plurality of the microcode iterative decode cycles.

10. The system of claim 9, wherein the at least one processor device initializes the at least one microcode iterative decode cycle on the buffered dataset when an uncorrectable read error occurs.

11. The system of claim 9, wherein pursuant to providing an error feedback loop, the at least one processor device builds upon data corrections obtained in a previous microcode iterative decode cycle for a next microcode iterative decode cycle.

12. The system of claim 9, wherein the at least one processor device initiates the x microcode iterative decode cycles on the buffered dataset until a predetermined error correction threshold is reached.

13. The system of claim 12, wherein the at least one processor device, upon reaching the predetermined error correction threshold, rereads data of the buffered dataset from the tape following a backhitch reposition.

14. The system of claim 13, wherein the at least one processor device, upon rereading the data of the buffered dataset from the tape, changes at least one of a plurality of read configuration characteristics.

15. The system of claim 14, wherein the at least one processor device monitors and tracks at least one of a sub-dataset uncorrectable error status (UE) and an accumulated correction count (CORCNT) of attempted error corrections.

16. The system of claim 9, wherein the at least one processor device maintains at least one of a log counter and a tape map histogram of successful and unsuccessful attempts of the at least one microcode iterative decode cycle.

17. A computer program product for data error recovery in a tape storage system by at least one processor device, the computer program product embodied on a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

an executable portion that, in a tape storage system using an iterative hardware decoder, dynamically initializes at least one microcode iterative decode cycle on a buffered dataset, each iterative decode cycle providing an error feedback loop;

an executable portion that initiates n microcode iterative decode cycles on the buffered dataset while tape is at speed;

wherein n comprises a number of microcode iterative decode cycles able to complete without stopping the tape due to buffering; and

an executable portion that initiates x microcode iterative decode cycles on the buffered dataset while the tape is stopped;

wherein x comprises at least one of a plurality of the microcode iterative decode cycles.

18. The computer program product of claim 17, further comprising an executable portion that initializes the at least one microcode iterative decode cycle on the buffered dataset when an uncorrectable read error occurs.

19. The computer program product of claim 17, pursuant to providing an error feedback loop, further comprises an executable portion that builds upon data corrections obtained in a previous microcode iterative decode cycle for a next microcode iterative decode cycle.

20. The computer program product of claim 17, further comprising an executable portion that initiates the x microcode iterative decode cycles on the buffered dataset until a predetermined error correction threshold is reached.

21. The computer program product of claim 20, further comprising an executable portion that, upon reaching the predetermined error correction threshold, rereads data of the buffered dataset from the tape following a backhitch reposition.

22. The computer program product of claim 21, further comprising an executable portion that, upon rereading the data of the buffered dataset from the tape, changes at least one of a plurality of read configuration characteristics.

23. The computer program product of claim 22, further comprising an executable portion that monitors and tracks at least one of a sub-dataset uncorrectable error status (UE) and an accumulated correction count (CORCNT) of attempted error corrections.

24. The computer program product of claim 17, further comprising an executable portion that maintains at least one of a log counter and a tape map histogram of successful and unsuccessful attempts of the at least one microcode iterative decode cycle.