Flash Threshold Voltage Management for Faster Error-Resilient Reads
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Solution Overview
Problem
Existing methods for managing threshold voltage in NAND flash storage result in time-consuming operations that delay read and write processes, and frequent uncorrectable bit errors lead to significant performance degradation.
Innovation Solution
A method for periodically scanning and managing threshold voltage by establishing an optimal threshold voltage table, using a specific region with pre-determined cell state distribution information, and updating the table based on offset parameters to minimize read operations and correct errors efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time optimal threshold voltage scanning is performed, then uncorrectable bit error rate is reduced, but read and write operations are delayed
Solution Approach 1:
The patent pre-calculates and stores optimal threshold voltages in a lookup table before actual read operations occur. When reading flash data, the system directly queries the pre-computed table rather than performing real-time scanning, thus eliminating the time delay while maintaining error correction effectiveness
Solution Approach 2:
The patent performs optimal threshold voltage scanning periodically rather than continuously for every read operation. The lookup table is updated at predetermined intervals, balancing the need for accurate threshold voltage data with the requirement to minimize interference with normal read and write operations
2Reliability
If optimal threshold voltage scanning is performed frequently to reduce uncorrectable errors, then data reliability is improved, but overall system performance deteriorates
Solution Approach 1:
The system pre-computes optimal threshold voltages and stores them in a lookup table, eliminating the need for frequent real-time scanning. This preliminary preparation ensures data reliability is maintained while avoiding continuous performance degradation from repeated scanning operations
Solution Approach 2:
The patent creates a copy of the optimal threshold voltage data in a lookup table that can be quickly queried without affecting the original flash memory. This copying mechanism allows rapid retrieval of threshold voltage information without performing time-consuming scanning operations on the actual data
Data Source
AI summary
The present application provides a method for managing a threshold voltage, a method for reading flash data, a solid state disk controller, and a solid state disk. The method for managing a threshold voltage includes: acquiring a target block with a specific region, the specific region having a determined first piece of cell state distribution information; and when a preset scanning interval is reached, scanning the threshold voltage based on the specific region of the target block, the first piece of cell state distribution information, and an optimal threshold voltage table, and periodically managing the optimal threshold voltage table.