Shingled magnetic recording disk drive with multiple data zones containing different numbers of error-correction-code sectors

• US 8,699,162 B1
• Filed: 11/18/2012
• Issued: 04/15/2014
• Est. Priority Date: 11/18/2012
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Inventors: Grobis, Michael Konrad, Schabes, Manfred Ernst
• Primary Examiner(s): ALUNKAL, THOMAS D
• Application Number:
  US13/680,089
• Time in Patent Office: 513 Days
• Field of Search: 360/39, 360/48, 360/55, 360/75, 360/77.04, 360/45, 360/47
• US Class Current: 360/48
• CPC Class Codes: G11B 20/18 Error detection or correction; Testing , e.g. of drop-outs
• CPC Class Codes: G11B 5/09 Digital recording
• CPC Class Codes: G11B 5/5547 "Seek" control and circuits therefor G11B5/5556 takes precedence
• CPC Class Codes: G11B 5/5565 system adaptation for compensation of variations of physical parameters, e.g. temperature

Abstract

A shingled magnetic recording disk drive with sector error correction code (ECC) has the disk recording surface divided into multiple zones. Each zone is assigned a sector-ECC strength, i.e., a unique number of ECC sectors associated with a block of data sectors. The zone in which data is to be written is determined from the time average of the position-error signal (PES), which is an indication of the track misregistration (TMR) and thus the current environmental condition to which the HDD is subjected.

Claims

1. A shingled magnetic recording disk drive comprising:

a magnetic recording disk having a recording surface arranged in a plurality of annular zones, each zone having a plurality of concentric shingled data tracks containing data sectors, the recording surface also having a plurality of servo sectors containing position error signal (PES) fields extending generally radially across the shingled data tracks;

wherein each zone has a unique number of error correction code (ECC) sectors associated with a block of data sectors;

a write head associated with said disk surface for generating a magnetic write field to write data to the tracks;

a read head for reading data written in the tracks and for detecting the PES fields;

an actuator for moving the write head and read head to selected tracks;

servo electronics for decoding the PES fields into PES values;

a controller for controlling the writing of data by the write head to the tracks; and

memory coupled to the controller and containing a program of instructions readable by the controller for determining the zone in which to write data, the program of instructions undertaking the method acts comprising;

(a) assigning to each zone a range of PES values;

(b) determining a time average value of decoded PES values;

(c) selecting a zone for which the time average value of decoded PES values is within the range of PES values; and

(d) writing data to a block of data sectors in said selected zone, computing error correction bits for said written data, and writing the computed error correction bits to the ECC sectors in said selected zone, the number of ECC sectors written with the error correction bits corresponding to the unique number of ECC sectors associated with said selected zone.

2. The disk drive of claim 1 wherein the time average value of decoded PES values is the root-mean-squares (RMS) time average value.

3. The disk drive of claim 1 wherein the method acts further comprise, if the time average value of decoded PES values is greater than the greatest of PES values in said ranges, not performing steps (c) and (d) until the time average value of decoded PES values is less than the greatest of PES values in said ranges.

4. The disk drive of claim 1 wherein the concentric shingled data tracks in each zone are arranged in a plurality of annular bands, the bands being separated by annular inter-band gaps.

5. The disk drive of claim 1 wherein the annular bands comprise an extended cache region (E-region), wherein the data to be written to the E-region is stored in said memory, and wherein the controller retrieves the data to be written to the E-region from said memory.

6. The disk drive of claim 1 wherein the method acts further comprise, prior to selecting a zone, counting the number of seeks (NS) of the actuator moving the write head from one track to a non-adjacent track within a predetermined time period.

7. The disk drive of claim 6 wherein the method acts further comprise comparing NS to a predetermined value NS_max, and wherein selecting a zone comprises selecting a zone in response to said comparison.

8. The disk drive of claim 6 wherein assigning to each zone a range of PES values comprises storing in memory a first table of zone numbers and associated ranges of PES values and storing in memory a second table of zone numbers and associated ranges of PES values, and wherein selecting a zone comprises selecting one of said tables in response to the value of NS.

9. The disk drive of claim 1 wherein each zone contains a number of assigned data tracks, and wherein the method acts further comprise calculating the frequency of write operations to each zone and reapportioning the number of assigned data tracks to the zones in proportion to the calculated frequencies.

10. The disk drive of claim 9 wherein the act of calculating the frequency of write operations to each zone comprises calculating the amount of data written to each zone.

11. A shingled magnetic recording disk drive comprising:

a magnetic recording disk having a recording surface arranged in a number of annular zones Z0 through Zk where k is an integer greater than 0, each zone having a plurality of concentric shingled data tracks containing data sectors and arranged in a plurality of annular bands, the bands being separated by annular inter-band gaps, the recording surface also having a plurality of servo sectors containing position error signal (PES) fields extending generally radially across the shingled data tracks;

wherein each zone Zi has Ni error correction code (ECC) sectors associated with a block of data sectors, where i is the zone number and where Ni is different for each N0 through Nk;

a write head associated with said disk surface for generating a magnetic write field to write data to the tracks;

a read head for reading data written in the tracks and for detecting the PES fields;

an actuator for moving the write head and read head to selected tracks;

servo electronics for decoding the PES fields into PES values;

a controller for controlling the writing of data by the write head to the tracks; and

memory coupled to the controller and containing a program of instructions readable by the controller for determining the zone Zi in which to write data, the program of instructions undertaking the method acts comprising;

(a) assigning to each zone Zi a unique range of PES values;

(b) determining a time average value of decoded PES values;

(c) selecting a zone Zi for which the time average value of decoded PES values is within the range of PES values; and

(d) writing data to a block of data sectors in selected zone Zi and error correction bits associated with said written data to Ni ECC sectors in said selected zone Zi.

12. The disk drive of claim 11 wherein the time average value of decoded PES values is the root-mean-squares (RMS) time average value.

13. The disk drive of claim 11 wherein the greatest PES value in all of said ranges of PES values is PES_max, and wherein the method acts further comprise, if the time average value of decoded PES values is greater than PES_max, not performing steps (c) and (d) until the time average value of decoded PES values is less than PES_max.

14. The disk drive of claim 11 wherein the method acts further comprise, prior to selecting a zone, counting the number of seeks (NS) of the actuator moving the write head from one track to a non-adjacent track within a predetermined time period.

15. The disk drive of claim 14 wherein the method acts further comprise comparing NS to a predetermined value NS_max, and wherein selecting a zone comprises selecting a zone in response to said comparison.

16. The disk drive of claim 14 wherein assigning to each zone a range of PES values comprises storing in memory a first table of zone numbers and associated ranges of PES values and storing in memory a second table of zone numbers and associated ranges of PES values, and wherein selecting a zone comprises selecting one of said tables in response to the value of NS.

17. The disk drive of claim 11 wherein each zone contains a number of assigned data tracks, and wherein the method acts further comprise calculating the frequency of write operations to each zone and reapportioning the number of assigned data tracks to the zones in proportion to the calculated frequencies.

18. The disk drive of claim 17 wherein the act of calculating the frequency of write operations to each zone comprises calculating the amount of data written to each zone.