Adaptive Wear Leveling for Non-Volatile Memory Lifespan
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Solution Overview
Problem
Existing non-volatile memory systems face challenges in evenly distributing wear across memory cells to prevent premature failure, as different types of memory cells have varying endurance characteristics and access patterns, leading to uneven wear and potential early failure.
Innovation Solution
Implementing a combination of regional and inter-region wear leveling schemes, where regional wear leveling distributes wear within individual regions using deterministic or mathematical schemes, and inter-region wear leveling shifts data between regions based on wear indicators to avoid concentrated wear, using control circuits to manage logical to physical address mappings and optimize data placement according to expected access patterns and endurance limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If wear leveling is applied to distribute wear across memory cells, then memory lifespan is extended, but device complexity increases due to multiple wear leveling schemes
Solution Approach 1:
The memory system is divided into multiple regions, with regional wear leveling applied independently to each region. This segmentation allows simpler per-region management while achieving comprehensive wear distribution across the entire memory system, resolving the contradiction between extended lifespan and reduced complexity.
Solution Approach 2:
The patent introduces inter-region wear leveling as an additional dimension beyond intra-region wear leveling. By operating at multiple levels (regional and inter-regional), the system achieves comprehensive wear distribution without requiring complex single-level management, as each level handles wear distribution at its own granularity.
2Reliability
If inter-region wear leveling shifts data between regions based on wear indicators, then wear distribution is improved, but loss of time occurs due to additional data movement operations
Solution Approach 1:
Regional wear leveling is applied first within each region to achieve initial wear distribution before inter-region wear leveling operates. This preliminary action reduces the amount of data movement required at the inter-region level, as wear is already partially balanced within regions, thus reducing time loss while maintaining reliability.
Solution Approach 2:
The system applies wear leveling at multiple levels (regional and inter-regional), which may seem excessive but actually optimizes the balance between wear distribution and time cost. The regional level handles local wear balancing quickly, while inter-region level handles global distribution, dividing the time cost across two simpler operations rather than one complex operation.
Data Source
AI summary
A non-volatile storage apparatus includes a set of non-volatile memory cells and one or more control circuits in communication with the set of non-volatile memory cells. The one or more control circuits are configured to remap logical addresses to physical addresses of the set of non-volatile memory cells according to a plurality of placement mappings and to select a new placement mapping from the plurality of placement mappings according to a cost function associated with the new placement mapping.