ECC Codeword Majority Detection for Uncorrectable Read Recovery
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Solution Overview
Problem
Existing error correction systems struggle to recover data that exceeds the error correction capability of ECC, as they often fail to provide sufficient improvement in signal quality through re-reads, leading to uncorrectable data.
Innovation Solution
Implementing majority detection techniques, such as hard and soft majority detection, which involve retrying ECC codewords multiple times, accumulating retry values, and using majority voting or reliability information to reconstruct bit values and declare erasures, thereby providing additional input for error detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction systems perform multiple re-reads with modified read parameters, then the number of retries increases to attempt error recovery, but the error correction capability remains insufficient for marginal sectors with excessive errors
Solution Approach 1:
The system performs preliminary majority detection on retry values before final error correction. By accumulating multiple retry readings and performing majority voting in advance, the system prepares corrected data that can be decoded by ECC even when initial readings exceed correction capability, thus improving reliability without proportionally increasing retries
Solution Approach 2:
The patent introduces majority detection as an intermediary processing step between raw data reading and ECC decoding. This intermediary layer consolidates information from multiple retries through majority voting, producing a refined data set that ECC can then correct within its capability limits, effectively bridging the gap between insufficient signal quality and correction requirements
2Reliability
If the system increases the number of retries for marginal sectors, then more attempts are made to recover erroneous data, but the time required for error recovery operations increases significantly
Solution Approach 1:
The system performs preliminary majority detection and consolidation of retry values before submitting to ECC decoding. By preparing the data in advance through majority voting, the system reduces the need for excessive retries and can achieve successful recovery within the specified time-out period, thus improving success rate while controlling time loss
Solution Approach 2:
The system uses feedback from majority detection results to guide subsequent ECC decoding attempts. By monitoring the quality of consolidated data from retries and adjusting whether to continue retrying or proceed with decoding, the system optimizes the balance between recovery success and time consumption
3Reliability
If conventional systems rely solely on ECC decoding without majority detection, then the error correction process is simpler and faster, but data beyond ECC correction capability cannot be recovered
Solution Approach 1:
The error correction system is segmented into two distinct functional stages: majority detection/consolidation and ECC decoding. The majority detection stage processes multiple retry values independently to produce consolidated data, while the ECC stage performs correction on the consolidated input. This segmentation allows each component to operate within its optimal capability without requiring complete redesign of the entire system
Solution Approach 2:
The patent merges majority detection functionality with the existing ECC decoding pipeline. By integrating the majority voting mechanism as a preprocessing step that feeds directly into ECC decoding, the system combines two error handling approaches into a unified workflow, improving recovery capability while maintaining manageable overall system complexity
4Measurement precision
If the system performs hard majority detection on all retry values, then more reliable bit values are obtained, but the processing complexity and computational overhead increase
Solution Approach 1:
The system performs majority detection selectively rather than universally on all data. By applying majority voting primarily to marginal sectors that fail initial ECC decoding and have available retry values, the system achieves improved bit reliability where needed without incurring the full computational overhead across all data processing operations
Data Source
AI summary
One or more techniques provide majority detection in error recovery. Accordingly, a device retries reading an ECC codeword having one or more bits for a plurality of retries, and stores each retry. The device (“hard” majority detection) votes on a value of each bit of the codeword based on a majority of corresponding retry values in the plurality of corresponding retries. Also, the device (“soft” majority detection) may determine reliability information for a value of each bit of the codeword based on a reoccurrence ratio of corresponding retry values in the plurality of retries. The device may declare erasures based on the reliability information and a (dynamically adjusted) threshold of uncertainty, e.g., where an “uncertain” bit based on the threshold or any symbol with an “uncertain” bit is declared as an erasure.