Flash Memory Wear Leveling via Dynamic Spare Queue Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flash memory devices face challenges in prolonging their lifetime due to uneven erase counts across blocks, leading to potential block damage from excessive erase operations, which existing technologies fail to adequately address through effective wear leveling.
Innovation Solution
A controller-managed data storage system that implements a spare queue and garbage collection with wear leveling, where blocks with high erase counts are identified and either frozen or used for cold data storage, and blocks with lower erase counts are allocated for new data, ensuring balanced usage and extending the memory's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional garbage collection is performed without wear leveling consideration, then storage space is recovered, but blocks with high erase counts are damaged leading to reduced device lifetime
Solution Approach 1:
The patent introduces wear level thresholds (overused lower threshold, overused higher threshold, clean threshold) as parameters to control garbage collection behavior. When spare block count falls below the clean threshold and high-erase-count blocks exist in the spare queue, the system performs wear-leveling-aware garbage collection, selecting blocks for erasure based on their erase count rather than arbitrary selection, thereby extending device lifetime while maintaining storage capacity.
2Reliability
If wear leveling is implemented by freezing high-erase-count blocks, then block durability is improved, but storage capacity and performance deteriorate due to reduced available blocks
Solution Approach 1:
The patent implements dynamic block management where blocks transition between different states (spare queue, data blocks, frozen blocks) based on real-time conditions. The freeze decision is not static but dynamically adjusted based on whether the spare queue count is below the clean threshold and whether high-erase-count blocks exist. This dynamic approach ensures that blocks are only frozen when necessary for wear leveling, minimizing impact on storage capacity while maximizing durability benefits.
3Quantity of substance
If frequent garbage collection is performed to maintain storage capacity, then available space is maintained, but erase operations increase causing accelerated wear on blocks
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring the spare queue block count and comparing it against the clean threshold. The system also tracks erase counts of individual blocks. This feedback loop enables intelligent decision-making: garbage collection is triggered only when the spare queue is low and wear leveling is needed, rather than performing frequent unnecessary erasures. This feedback-controlled approach maintains storage capacity while minimizing unnecessary wear from excessive garbage collection operations.
Data Source
AI summary
A FLASH memory control technique with wear leveling between the different blocks of the FLASH memory. By a controller managing the blocks of a FLASH memory within a data storage device, some of the blocks are pushed into a spare queue waiting to be allocated as data blocks or system blocks. When the number of blocks within the spare queue is lower than a clean threshold and any block within the spare queue has an erase count greater than an overused lower threshold, the controller performs a garbage correction operation with wear leveling between the different blocks.