Memory Controller Wear Leveling via Data Update Count
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Solution Overview
Problem
Existing memory systems face reduced lifespan due to uneven wear distribution across memory blocks, as erase operations are concentrated on certain blocks, leading to premature degradation, which is not effectively addressed by relying solely on erase count for wear leveling.
Innovation Solution
A controller that determines candidate blocks based on erase counts and further selects a victim block based on data update counts, moving data from the victim block to a destination block with higher erase counts to evenly distribute wear across memory blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wear leveling is performed based solely on erase counts, then the selection process is simple, but the wear distribution remains uneven and lifespan is reduced
Solution Approach 1:
The patent changes the selection parameters for wear leveling from solely erase count to a multi-dimensional criterion including erase count, data update count, and read count. This parameter expansion allows the system to select victim blocks more intelligently, avoiding blocks with high data activity that would benefit from frequent rewrites, thereby improving wear distribution and extending memory lifespan.
Solution Approach 2:
The patent introduces dynamic adjustment of wear leveling strategies based on real-time monitoring of data update counts and read counts. The system dynamically identifies hot blocks (high update/read activity) and cold blocks (low activity), and adjusts victim block selection accordingly, making the wear leveling process adaptive rather than static.
2Reliability
If data is moved frequently to balance wear, then wear distribution improves, but performance degrades due to increased operations
Solution Approach 1:
The patent applies local quality by treating different memory blocks differently based on their activity characteristics. Hot blocks (high data update count) are protected from being selected as victim blocks, while cold blocks (low activity) are preferentially selected. This localized differentiation ensures that wear leveling operations are performed only where they are most beneficial, avoiding unnecessary data movements and preserving performance.
Solution Approach 2:
By introducing data update count and read count as additional parameters beyond erase count, the system can make more informed decisions about which blocks to select as victims. This prevents the selection of blocks that are frequently accessed or updated, thereby reducing the number of unnecessary data movement operations and maintaining higher system performance.
3Reliability
If blocks with low erase counts are selected as victims, then wear leveling is achieved, but high-erase-count blocks continue to degrade prematurely
Solution Approach 1:
The patent performs preliminary analysis of block characteristics (data update count, read count) before selecting victim blocks. By proactively identifying hot blocks and preventing their selection as victims, the system protects high-erase-count blocks from further premature degradation. This preliminary screening ensures that only appropriate cold blocks are selected, extending the effective lifespan of actively used blocks.
Data Source
AI summary
A method for operating a controller for controlling a memory device including memory blocks, the method includes: determining candidate blocks based on erase counts of the memory blocks; determining a victim block among the candidate blocks based on data update counts of logical addresses associated with a plurality of pages in each of the candidate blocks; and moving data of the victim block into a destination block.