Erasure-Coded Data Storage for Problematic Pattern Recording

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Solution Overview

Problem

Data storage devices face challenges in maintaining a high signal-to-noise ratio (SNR) due to problematic patterns during recording and readback operations, which can lead to errors in error correction codes, especially in magnetic media where high-frequency patterns degrade the quality of data.

Innovation Solution

The implementation of an erasure encoding technique where problematic patterns are relocated to an erasure region within a block, generating an erasure codeword that is stored without the problematic patterns, allowing for their regeneration during read operations, thereby maintaining SNR and improving data integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If problematic patterns are recorded on magnetic media, then data can be stored, but the signal-to-noise ratio deteriorates due to high-frequency patterns

Engineering Contradiction:

Improvedata storage capacityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent extracts problematic patterns from the data stream before encoding. Specifically, problematic patterns are identified and removed from the input data block, then an erasure codeword is generated from the remaining good patterns. During readback, the erasure decoder regenerates the problematic patterns from the erasure codeword, preventing them from degrading the signal-to-noise ratio while preserving data storage capacity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary identification and removal of problematic patterns before the data is encoded and stored. By proactively identifying problematic patterns in advance and excluding them from the recorded data, the system prevents SNR degradation before it occurs, rather than attempting to correct it after readback.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If erasure encoding is used to remove problematic patterns, then signal-to-noise ratio is maintained, but device complexity increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidencoding complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the data processing into distinct stages: identification of problematic patterns, removal of those patterns, generation of erasure codeword from remaining patterns, and separate decoding/regeneration stages. This segmentation allows each component to be optimized independently and makes the overall complex process more manageable and implementable.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The erasure codeword serves as an intermediary structure that contains information about the good patterns without including the problematic patterns. This intermediary representation allows the system to maintain SNR by not recording problematic patterns while still enabling their regeneration through the decoding process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20220398153A1Data storage device processing problematic patterns as erasures

Publication Date: 2022.12.15 WESTERN DIGITAL TECHNOLOGIES INC

AI summary

A data storage device is disclosed comprising a non-volatile storage medium (NVSM). Problematic patterns in a block of input data are identified, and the problematic patterns are relocated from an initial location to an erasure region of the block to generate a modified block. The modified block is erasure encoded into an erasure codeword, at least part of the erasure codeword is stored in the NVSM.