Flash Memory Wear Leveling via Erase Count Tracking
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Solution Overview
Problem
Conventional flash memory access methods fail to evenly utilize blocks, leading to inefficient operation and potential data errors due to excessive erase counts, as blocks can only be accurately programmed when their erase count is below a threshold.
Innovation Solution
A method that divides flash memory into data and spare regions, where data blocks are managed with an erase count system, allowing for error correction and re-mapping of data between blocks to distribute wear evenly, thereby extending the operational lifespan of flash memory blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flash memory access methods are used, then data storage and retrieval operations can be performed, but blocks are not evenly utilized leading to excessive erase counts and potential data errors
Solution Approach 1:
The patent changes the parameter of erase count tracking and uses it as a basis for re-mapping decisions. By monitoring erase counts and reallocating blocks based on these parameters, the system ensures data accuracy is maintained while evenly distributing wear across all blocks, preventing any single block from reaching its erase limit prematurely.
Solution Approach 2:
The patent introduces a wear-leveling mechanism as an intermediary between data storage operations and physical block usage. This intermediary layer tracks erase counts and performs re-mapping to distribute wear evenly, thereby extending block lifespan without compromising data storage and retrieval operations.
2Productivity
If blocks are reused after reaching erase threshold, then storage capacity is maintained, but programming accuracy deteriorates and errors occur
Solution Approach 1:
The patent monitors erase count as a critical parameter and uses it to determine when to re-map data to new blocks. By tracking this parameter and acting before the threshold is exceeded, the system maintains programming accuracy while ensuring continuous storage capacity through proactive block management rather than reactive replacement.
Solution Approach 2:
The patent performs preliminary wear-leveling operations by tracking erase counts and re-mapping data to fresh blocks before the erase threshold is reached. This preliminary action prevents programming errors from occurring in the first place, maintaining accuracy while preserving storage capacity through advance block allocation planning.
3Duration of action of stationary object
If even block usage is implemented through re-mapping, then block lifespan is extended, but system complexity increases due to erase count tracking and re-mapping operations
Solution Approach 1:
The patent uses erase count as a simple, trackable parameter that requires minimal storage and processing. By basing the wear-leveling decision on this single parameter rather than complex analysis of block history or performance metrics, the system extends block lifespan while keeping the control logic relatively simple and efficient.
Data Source
AI summary
Methods and devices capable of erasing a flash memory evenly are provided, in which a flash memory comprises a data region with a plurality of data blocks and a spare region with a plurality of spare blocks, and a controller retrieves a corresponding data with a check code from a first data block of the flash memory according to a read command from a host, performs a predetermined check to the corresponding data by the check code, determines whether an error is correctable when a check result of the predetermined check represents that the error has occurred, and increases an erase count of the first data block by a predetermined value when the error is correctable.