Segment-based outer code recovery

Patent metadata

Field	Value
Publication number	US-10140180-B1
Application number	US-201615344423-A
Country	US
Kind code	B1
Filing date	Nov 4, 2016
Priority date	Nov 4, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

Systems and methods are disclosed for performing segment-based outer code recovery at a data storage device. An apparatus may comprise a circuit configured to disable outer code error recovery, and perform a read operation spanning a plurality of segments of a data storage medium, a segment including a plurality of sectors. The circuit may identify one or more segments from the plurality of segments that have one or more sectors with an error. For an identified segment of the one or more segments, the circuit may perform a re-read operation with outer code error recovery enabled, and perform outer code recovery on sectors with an error within the identified segment.

First claim

What is claimed is:

1. An apparatus comprising:
a circuit configured to:
disable outer code error recovery;
perform a read operation spanning a plurality of segments of a data storage medium, a segment including a plurality of sectors;
identify one or more segments, from the plurality of segments, that have one or more sectors with an error;
for an identified segment of the one or more segments, perform a re-read operation of the identified segment with outer code error recovery enabled, the re-read operation includes reading all sectors of the identified segment except for sectors with an error; and
perform outer code recovery on the sectors with an error in the identified segment.

2. The apparatus of claim 1 comprising the circuit further configured to:
zero out a syndrome state for the identified segment, the syndrome state being a value derived from sectors of the identified segment;
update the syndrome state with information from sectors of the identified segment obtained during the re-read operation; and
perform the outer code recovery based on the syndrome state.

3. The apparatus of claim 1 comprising the circuit further configured to:
determine a range of sectors to read during the read operation;
determine whether the range of sectors are located in a segment-based zone of a data storage medium;
disable the outer code recovery when the range of sectors are located in the segment-based zone; and
do not disable the outer code recovery when the range of sectors are not located in the segment-based zone.

4. The apparatus of claim 3 further comprising:
the data storage medium includes a magnetic disc; and
the circuit further configured to record data to the magnetic disc using shingled magnetic recording.

5. The apparatus of claim 1 further comprising:
a segment includes a storage area not defined by a data track of a data storage medium.

6. The apparatus of claim 1 comprising the circuit further configured to:
perform iterative outer code recovery on the sectors with an error in the identified segment, iterative outer code recovery including iterating between outer code recovery and inner code recovery.

7. The apparatus of claim 1 comprising the circuit further configured to:
repeat the re-read operation and outer code recovery for each segment of the one or more segments.

8. The apparatus of claim 1 comprising the circuit further configured to:
perform error recovery methods not including outer code recovery prior to performing the re-read operation.

9. The apparatus of claim 1 comprising the circuit further configured to:
perform the read operation further includes attempting to read all sectors requested in the read operation without halting due to failed sector reads.

10. A method comprising:
determining a range of sectors to read during a read operation;
determining whether the range of sectors are located in a segment-based zone of a data storage medium, a segment including a storage area of a plurality of sectors that is not track-based;
not disabling outer code recovery to perform the read operation when the range of sectors are not located in the segment-based zone;
when the range of sectors are located in the segment-based zone, perform the read operation including:
disabling outer code error recovery;
performing the read operation spanning a plurality of segments of the segment-based zone;
identifying one or more segments, from the plurality of segments, that have one or more sectors with an error;
for an identified segment of the one or more segments, performing a re-read operation of the identified segment with outer code error recovery enabled; and
performing outer code recovery on sectors with an error in the identified segment.

11. The method of claim 10 further comprising:
zeroing out a syndrome state for the identified segment, the syndrome state being a value derived from sectors of the identified segment;
updating the syndrome state with information from sectors of the identified segment obtained during the re-read operation; and
performing the outer code recovery based on the syndrome state.

12. The method of claim 10 further comprising:
performing iterative outer code recovery on the sectors with an error in the identified segment, including iterating between outer code recovery and inner code recovery.

13. The method of claim 10 further comprising:
the re-read operation includes reading all sectors of the identified segment except for the sectors with an error,
repeating the re-read operation and outer code recovery for each segment of the one or more segments.

14. A device comprising:
a digital communications channel configured to:
perform a read operation spanning a plurality of segments of a data storage medium with outer code recovery disabled, including attempting to read all sectors requested in the read operation without halting due to failed sector reads, a segment including a plurality of sectors and less than a data track of a data storage medium;
identify one or more segments, from the plurality of segments, that failed to read;
for an identified segment of the one or more segments, perform a re-read operation with outer code error recovery enabled; and
perform outer code recovery on sectors that failed to read in the identified segment.

15. The device of claim 14 comprising the digital communications channel further configured to:
zero out a syndrome state for the identified segment, the syndrome state being a value derived from sectors of the identified segment;
update the syndrome state with information from sectors of the identified segment obtained during the re-read operation; and
perform the outer code recovery based on the syndrome state.

16. The device of claim 15 further comprising:
perform the read operation further includes attempting to read all sectors requested in the read operation without halting due to failed sector reads;
the re-read operation includes reading all sectors of the identified segment except for the sectors with an error; and
the digital communications channel further configured to repeat the re-read operation and outer code recovery for each segment of the one or more segments.

17. The device of claim 16 comprising the digital communications channel further configured to:
determine a range of sectors to read during the read operation;
determine whether the range of sectors are located in a segment-based zone of the data storage medium;
disable the outer code recovery when the range of sectors are located in the segment-based zone; and
do not disable the outer code recovery when the range of sectors are not located in the segment-based zone.

18. The device of claim 17 comprising the digital communications channel further configured to:
perform iterative outer code recovery on the sectors that failed to read in the identified segment, iterative outer code recovery including iterating between outer code recovery and inner code recovery.

Assignees

• Seagate Technology Llc

Inventors

• Sridhara Deepak
• Patapoutian Ara
• Reddy Prafulla B

Classifications

• H03M13/05 Primary

  using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits {(H03M13/2906 takes precedence)} · CPC title

• G06F11/1076 Primary

  Parity data used in redundant arrays of independent storages, e.g. in RAID systems · CPC title

• G11B20/1833 Primary

  by adding special lists or symbols to the coded information (G11B20/1806, G11B20/1866 take precedence) · CPC title

• H03M13/3715

  Adaptation to the number of estimated errors or to the channel state · CPC title

• H03M13/29

  combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes · CPC title