Flash Memory ECC with Selective Compression by Wear Level
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Solution Overview
Problem
Non-volatile memory devices, such as flash memory, experience increased error rates over time and usage cycles, necessitating enhanced error correction performance to maintain data integrity.
Innovation Solution
A method and apparatus that selectively compress data and store it along with an error correction code (ECC) based on the deterioration status of the memory device's physical areas, ensuring that areas with higher deterioration receive compressed data and ECC, while areas with lower deterioration store uncompressed data and ECC, maintaining ECC size consistency across both scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored uncompressed in non-volatile memory devices, then storage speed and simplicity are maintained, but error correction performance deteriorates over time as the number of use increases
Solution Approach 1:
The patent applies local quality by differentiating storage treatment based on the deterioration status of specific physical areas. Areas with higher deterioration status (more prone to errors) receive compressed data storage, while areas with lower deterioration status receive uncompressed data storage. This localized differentiation optimizes error correction performance without uniformly increasing system complexity across the entire storage device.
Solution Approach 2:
The patent changes the parameter of data compression status based on the deterioration status of memory areas. By dynamically adjusting whether data is compressed or uncompressed according to the specific characteristics of each storage area, the system adapts to varying error rates and optimizes reliability without requiring a complete system redesign.
2Reliability
If error correction codes are increased in size to improve error correction performance, then reliability is enhanced, but storage capacity and efficiency deteriorate
Solution Approach 1:
Instead of uniformly increasing ECC size across all storage areas, the patent applies local quality by selectively compressing data in areas with higher deterioration status. This allows the system to maintain appropriate ECC sizes while improving reliability in error-prone areas through compression rather than increasing ECC overhead.
Solution Approach 2:
The patent discards the need for larger ECC codes in favor of data compression in high-deterioration areas. By compressing data in areas prone to errors, the system recovers reliability without the overhead cost of proportionally larger error correction codes, thus preserving storage capacity.
3Reliability
If data compression is applied to all storage areas, then error correction performance is enhanced, but storage speed and write efficiency deteriorate
Solution Approach 1:
The patent applies local quality by selectively applying compression only to areas with deterioration status at or above a threshold value. Areas with lower deterioration status maintain uncompressed data storage, preserving high write speeds. This localized approach balances reliability improvement with productivity preservation.
Solution Approach 2:
Instead of applying compression universally (excessive action), the patent applies compression partially only to areas that need it most (high deterioration status areas). This partial action approach improves error correction performance where necessary while avoiding the performance penalty of compression in areas where it is not needed.
4Reliability
If different ECC sizes are used for different storage areas, then error correction performance is optimized, but device complexity and management overhead increase
Solution Approach 1:
The patent applies local quality by using a unified ECC size for all areas while differentiating data compression status based on local deterioration characteristics. This maintains ECC management simplicity while achieving localized optimization through compression rather than varying ECC parameters.
Solution Approach 2:
Instead of varying ECC sizes to achieve local optimization (complex management), the patent inverts the approach by keeping ECC size uniform and achieving local optimization through data compression status differentiation. This inversion simplifies management while maintaining the desired reliability optimization.
Data Source
AI summary
A method of enhancing an error correction performance in a data storage system, and a storage device using the method, determines a deterioration status of a physical area of a memory device to which data is to be stored and compresses data and stores the compressed data and an error correction code (ECC) with respect to the compressed data in an area of which the deterioration status is equal to or greater than a threshold value that is initially set and stores uncompressed data and an ECC with respect to the uncompressed data in an area of which the deterioration status is less than the threshold value.