Granted Patent B2

US 12,374,365 · App. 18/531,483 · Granted Jul 29, 2025

Inventors: Iouri Oboukhov (Rochester, MN); Richard Galbraith (Rochester, MN); Jonas Goode (Lake Forest, CA); Niranjay Ravindran (Rochester, MN); Jihoon Park (San Jose, CA)

Assignee: Western Digital Technologies, Inc.

G11B19/048G11B19/041G11B19/128G11B20/1813G11B20/182G11B20/1833G11B2020/185

Abstract

Claims (158)

1. A data storage device, comprising:

a non-volatile storage medium configured to store user data; and

a channel circuit configured to encode user data to and decode user data from the non-volatile storage medium using configuration settings that control the encoding and decoding of the user data, wherein:

at least one configuration setting is determined based on:

a mutual information metric based on a multi-bit symbol size; and

a target mutual information threshold for the mutual information metric;

user data is encoded in a plurality of codewords;

each codeword of the plurality of codewords is comprised of a plurality of symbols; and

the mutual information metric is based on:

calculating a mutual information value for each symbol of the plurality of symbols; and

aggregating the mutual information values for the plurality of symbols in each codeword.

2. The data storage device of claim 1 , wherein:

the channel circuit includes an error correction code encoder and decoder for storing user data based on an error correction code;

the error correction code includes codewords comprised of a plurality symbols and parity data corresponding to a code rate;

the mutual information metric defines an upper boundary of the code rate; and

the at least one configuration setting includes the error correction code having a selected code rate less than the mutual information metric.

3. The data storage device of claim 1 , wherein:

the channel circuit includes a modulation code encoder and decoder for storing user data based on a modulation code;

the modulation code includes run length limited codewords defining a code penalty;

the mutual information metric comprises a comparison of:

data written with the modulation code; and

data written without the modulation code; and

the at least one configuration setting includes the modulation code having a selected code penalty to meet the target mutual information threshold.

4. The data storage device of claim 1 , wherein:

the channel circuit includes a disk format for storing user data based on a track pitch parameter and a bit density parameter;

a combination of the track pitch parameter and the bit density parameter determines an areal density of the non-volatile storage medium;

the mutual information metric correlates to the areal density; and

the at least one configuration setting includes the track pitch parameter and the bit density parameter having a selected areal density to meet the target mutual information threshold.

5. The data storage device of claim 4 , wherein:

the non-volatile storage medium is divided into a plurality of zones;

the at least one configuration setting includes, for each zone of the plurality of zones:

the track pitch parameter and the bit density parameter;

a selected code rate for an error correction code; and

a modulation code; and

the mutual information metric is calculated for each zone of the plurality of zones.

6. The data storage device of claim 1 , wherein:

the non-volatile storage medium is divided into a plurality of sectors;

each sector in the plurality of sectors is comprised of a plurality of symbols;

the mutual information metric is based on:

calculating a mutual information value for each symbol of the plurality of symbols; and

aggregating the mutual information values for the plurality of symbols in each sector; and

the mutual information metric correlates to a sector failure rate and is independent of error correction code rate and linear density.

7. A system comprising the data storage device of claim 1 and further comprising:

a tester comprising:

a tester processor;

a tester memory; and

a storage device interface configured to communicate with the data storage device, wherein the tester is configured to:

determine a proposed set of configuration settings, wherein the proposed set of configuration settings includes the at least one configuration setting;

determine the multi-bit symbol size based on an inter-symbol interference threshold for the proposed set of configuration settings;

determine the target mutual information threshold; and

calculate the mutual information metric based on the proposed set of configuration settings and a plurality of symbols having the multi-bit symbol size.

8. The system of claim 7 , wherein the tester is further configured to:

determine a plurality of sectors on the non-volatile storage medium;

determine a set of sector symbols for each sector of the plurality of sectors;

determine, based on the set of sector symbols for that sector, a sector mutual information metric for each sector of the plurality of sectors;

determine a mutual information variance of the sector mutual information metric for each sector; and

determine a predicted sector failure rate based on the mutual information variance for that sector.

9. The data storage device of claim 1 , wherein:

the channel circuit comprises at least one signal processing filter; and

the channel circuit is further configured to:

iteratively determine the mutual information metric based on a range of tap settings of the at least one signal processing filter; and

determine, responsive to the mutual information metric meeting the target mutual information threshold, a set of tap settings of the at least one signal processing filter.

10. A method comprising:

determining, for a data storage device, a mutual information metric based on a multi-bit symbol size;

determining a target mutual information threshold for the mutual information metric; and

configuring, based on a comparison of the mutual information metric and the target mutual information threshold, at least one configuration setting for a channel circuit of the data storage device, wherein:

the channel circuit is configured to encode user data and decode user data from a non-volatile storage medium of the data storage device;

the channel circuit includes an error correction code encoder and decoder for storing user data based on an error correction code;

the error correction code includes codewords comprised of a plurality symbols and parity data corresponding to a code rate;

the mutual information metric defines an upper boundary of the code rate; and

the at least one configuration setting includes the error correction code having a selected code rate less than the mutual information metric.

11. The method of claim 10 , wherein:

the channel circuit includes a modulation code encoder and decoder for storing user data based on a modulation code;

the modulation code includes run length limited codewords defining a code penalty;

the mutual information metric comprises a comparison of:

data written with the modulation code; and

data written without the modulation code; and

the at least one configuration setting includes the modulation code having a selected code penalty to meet the target mutual information threshold.

12. The method of claim 10 , wherein:

the channel circuit includes a disk format for storing user data based on a track pitch parameter and a bit density parameter;

a combination of the track pitch parameter and the bit density parameter determines an areal density of the non-volatile storage medium;

the mutual information metric correlates to the areal density; and

the at least one configuration setting includes the track pitch parameter and the bit density parameter having a selected areal density to meet the target mutual information threshold.

13. The method of claim 12 , wherein:

the non-volatile storage medium is divided into a plurality of zones;

the at least one configuration setting includes, for each zone of the plurality of zones:

the track pitch parameter and the bit density parameter;

a selected code rate for an error correction code; and

a modulation code; and

the mutual information metric is calculated for each zone of the plurality of zones.

14. The method of claim 10 , wherein:

user data is encoded in a plurality of codewords;

each codeword of the plurality of codewords is comprised of a plurality of symbols; and

determining the mutual information metric comprises:

calculating a mutual information value for each symbol of the plurality of symbols; and

aggregating the mutual information values for the plurality of symbols in each codeword.

15. The method of claim 10 , wherein:

the non-volatile storage medium is divided into a plurality of sectors;

each sector in the plurality of sectors is comprised of a plurality of symbols;

determining the mutual information metric comprises:

calculating a mutual information value for each symbol of the plurality of symbols; and

aggregating the mutual information values for the plurality of symbols in each sector; and

the mutual information metric correlates to a sector failure rate and is independent of error correction code rate and linear density.

16. The method of claim 10 , further comprising:

determining a proposed set of configuration settings for the channel circuit, wherein the proposed set of configuration settings includes the at least one configuration setting;

determining the multi-bit symbol size based on an inter-symbol interference threshold for the proposed set of configuration settings; and

calculating the mutual information metric based on the proposed set of configuration settings and a plurality of symbols having the multi-bit symbol size.

17. The method of claim 16 , further comprising:

determining a plurality of sectors on the non-volatile storage medium;

determining a set of sector symbols for each sector of the plurality of sectors;

determining, based on the set of sector symbols for that sector, a sector mutual information metric for each sector of the plurality of sectors;

determining a mutual information variance of the sector mutual information metric for each sector; and

determining a predicted sector failure rate based on the mutual information variance for that sector.

18. A system comprising:

a processor;

a memory;

means for determining, for a data storage device, a mutual information metric based on a multi-bit symbol size;

means for determining a target mutual information threshold for the mutual information metric; and

means for configuring, based on a comparison of the mutual information metric and the target mutual information threshold, at least one configuration setting for a channel circuit of the data storage device, wherein:

the channel circuit comprises at least one signal processing filter; and

the channel circuit is configured to:

encode user data and decode user data from a non-volatile storage medium of the data storage device;

iteratively determine the mutual information metric based on a range of tap settings of the at least one signal processing filter; and

determine, responsive to the mutual information metric meeting the target mutual information threshold, a set of tap settings of the at least one signal processing filter.

19. A data storage device, comprising:

a non-volatile storage medium configured to store user data; and

a channel circuit configured to encode user data to and decode user data from the non-volatile storage medium using configuration settings that control the encoding and decoding of the user data, wherein:

at least one configuration setting is determined based on:

a mutual information metric based on a multi-bit symbol size; and

a target mutual information threshold for the mutual information metric;

the channel circuit includes a modulation code encoder and decoder for storing user data based on a modulation code;

the modulation code includes run length limited codewords defining a code penalty;

the mutual information metric comprises a comparison of:

data written with the modulation code; and

data written without the modulation code; and

the at least one configuration setting includes the modulation code having a selected code penalty to meet the target mutual information threshold.

20. A data storage device, comprising:

a non-volatile storage medium configured to store user data; and

a channel circuit configured to encode user data to and decode user data from the non-volatile storage medium using configuration settings that control the encoding and decoding of the user data, wherein:

at least one configuration setting is determined based on:

a mutual information metric based on a multi-bit symbol size; and

a target mutual information threshold for the mutual information metric;

the channel circuit includes a disk format for storing user data based on a track pitch parameter and a bit density parameter;

a combination of the track pitch parameter and the bit density parameter determines an areal density of the non-volatile storage medium;

the mutual information metric correlates to the areal density; and

the at least one configuration setting includes the track pitch parameter and the bit density parameter having a selected areal density to meet the target mutual information threshold.

21. A data storage device, comprising:

a non-volatile storage medium configured to store user data; and

a channel circuit configured to encode user data to and decode user data from the non-volatile storage medium using configuration settings that control the encoding and decoding of the user data, wherein:

at least one configuration setting is determined based on:

a mutual information metric based on a multi-bit symbol size; and

a target mutual information threshold for the mutual information metric;

the non-volatile storage medium is divided into a plurality of sectors;

each sector in the plurality of sectors is comprised of a plurality of symbols;

the mutual information metric is based on:

calculating a mutual information value for each symbol of the plurality of symbols; and

aggregating the mutual information values for the plurality of symbols in each sector; and

the mutual information metric correlates to a sector failure rate and is independent of error correction code rate and linear density.

Assignments (3)

Continuity (2)

References Cited (40)