Static Wear Leveling for Non-Volatile Flash Memory Blocks
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Solution Overview
Problem
Existing non-violate storage devices experience uneven block erasure counts, leading to premature wear and shortened lifespan as some blocks are used more frequently than others, causing a few blocks to have significantly higher erasure counts while most have lower counts.
Innovation Solution
A method for static wear leveling that involves maintaining occupied and erasure count blocks, triggering wear leveling when a difference in erasure counts exceeds a threshold, and swapping data from blocks with higher occupied counts and lower erasure counts to balance usage across all blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is stored in flash memory blocks without wear leveling, then write speed is improved, but block erasure count becomes uneven leading to shortened device lifespan
Solution Approach 1:
The patent maintains erasure count blocks that record the erasure count of all physical blocks in advance. Before data movement operations, the wear leveling trigger judgment unit checks these pre-maintained counts to determine if wear leveling is needed, allowing proactive balancing before uneven wear causes failure
Solution Approach 2:
The patent implements a feedback mechanism where the wear leveling trigger judgment unit continuously monitors erasure count differences between free blocks and using blocks. When the difference exceeds a threshold, the system triggers data movement operations to redistribute data, creating a closed-loop control that maintains uniform wear distribution across all blocks
2Reliability
If wear leveling operations are performed frequently to balance erasure counts, then device lifespan is extended, but system complexity increases
Solution Approach 1:
The patent applies wear leveling selectively rather than uniformly across all blocks. The judgment unit triggers wear leveling only when the erasure count difference between free and using blocks exceeds a specific threshold, applying the balancing operation locally where needed rather than globally, thus reducing unnecessary operations and system complexity
Solution Approach 2:
The system uses the existing block structure and erasure count information already maintained for other purposes. By reusing the erasure count blocks and existing data movement capabilities, the wear leveling function serves itself using existing resources rather than requiring entirely new hardware or complex external control mechanisms
Data Source
AI summary
A method for static wear leveling in non-violate storage device is disclosed. Use the method to balance all blocks' erasure counts to avoid most blocks having smaller erasure count and several blocks having larger erasure count to shorten the life time of the device.