Storage Controller Parity Interruption for Faster Read Error Recovery
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Solution Overview
Problem
Storage devices, such as magnetic disk devices, face challenges in recovering from read errors, particularly Sync-Mark detection errors, which prolong recovery times due to inefficient decoding processes and increased processing times during iterative decoding attempts.
Innovation Solution
The implementation of a storage device with a controller that performs parity checks on data segments and interrupts decoding when a parity violation threshold is exceeded, allowing for adaptive shifting of decoding start positions and optimizing the forcible search process to reduce recovery time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller executes parity checks on all data segments without interruption to ensure accurate error detection, then the reliability of error detection is improved, but the recovery time for read errors increases
Solution Approach 1:
The controller skips or interrupts the parity check process when a predetermined number of parity violations are detected, rather than completing checks on all remaining data segments. This allows the system to rush through the error detection process early, identifying read errors quickly without investing excessive time in futile complete verification, thereby reducing recovery time while maintaining reliable error detection.
Solution Approach 2:
The controller performs partial parity checks on data segments until a threshold of parity violations is reached, then interrupts further checking. This partial action approach is sufficient to detect read errors with high reliability while avoiding the excessive time consumption of completing all parity checks, even when errors are already evident from partial results.
2Reliability
If the controller performs multiple iterative decoding attempts to ensure complete data recovery, then the reliability of data recovery is improved, but the processing time increases
Solution Approach 1:
The controller performs a predetermined number of iterative decoding attempts, which is sufficient to achieve reliable data recovery in most cases, then stops further iterations. This partial action approach maintains high data recovery reliability while avoiding excessive processing time that would result from unlimited iterative attempts, especially when the error is already detected through parity violation interruption.
Solution Approach 2:
The controller performs preliminary parity checks and error detection before committing to extensive iterative decoding processes. By detecting errors early through interrupted parity checks, the system can make informed decisions about whether full iterative decoding is necessary, reducing unnecessary processing time while maintaining recovery reliability for cases that do require full decoding attempts.
3Reliability
If the controller executes forcible search with multiple offset shifts to locate valid data positions, then the reliability of data location is improved, but the number of decoding trials and processing time increase
Solution Approach 1:
The controller performs forcible search with offset shifts only when necessary, based on preliminary error detection results. When parity violations indicate read errors, the controller executes a predetermined number of forcible search attempts with different offset positions to locate valid data. This partial action approach ensures reliable data location while avoiding excessive decoding trials, as the search is limited to a predetermined number of attempts rather than exhaustive searching.
Solution Approach 2:
The controller performs preliminary parity violation detection before initiating forcible search operations. This preliminary action allows the system to identify when forcible search is actually needed (when read errors are detected) versus when normal decoding suffices, thereby improving data location reliability only when necessary and maintaining high decoding productivity in error-free cases.
Data Source
AI summary
A storage device includes a recording medium, a first memory storing first data read from the recording medium, and a controller. The controller searches for read target data in the first data by executing a parity check on second data that is in the first data and starts at a first position, while executing the parity check, determining whether or not an interruption condition is satisfied, storing the second data in a second memory when the parity check completes without the interruption condition being satisfied and a result of a completed parity check satisfies a first condition, and executing a parity check on third data that is in the first data and starts at a second position, responsive to the interruption condition being satisfied and responsive to the result of the completed parity check not satisfying the first condition.