Flash Package Storage System Hierarchical Wear Leveling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In large-capacity storage systems using flash memory, wear leveling control overhead increases due to a large number of flash memory chips, and capacity reduction through capacity virtualization is not efficient, especially when page size must be made larger to maintain sequential access performance.
Innovation Solution
Implementing hierarchical wear leveling and capacity virtualization, where higher-level wear leveling is managed at the page unit and lower-level wear leveling and capacity virtualization are managed within flash packages, allowing for efficient reduction of block deletion imbalances and capacity reduction without significant performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wear leveling is implemented across all flash memory chips in large-capacity storage systems, then the imbalance of block deletions is reduced, but the control overhead increases significantly
Solution Approach 1:
The patent divides the wear leveling control into two hierarchical levels: package-level wear leveling that operates within each flash package to balance block deletions among chips in the same package, and storage system-level wear leveling that operates across multiple packages. This segmentation reduces the control overhead by localizing the wear leveling operations at the package level rather than requiring centralized control over all chips in the storage system.
2Loss of substance
If capacity virtualization is implemented with smaller page sizes, then the capacity reduction efficiency is improved, but the sequential access performance deteriorates
Solution Approach 1:
The patent introduces a hierarchical capacity virtualization structure with two levels: package-level capacity virtualization that operates within each flash package using smaller page sizes to improve capacity reduction efficiency, and storage system-level capacity virtualization that operates across multiple packages using larger page sizes to maintain sequential access performance. This dimensional separation allows the system to simultaneously achieve both capacity reduction efficiency and performance.
Data Source
AI summary
A storage system 100, which has a plurality of flash packages 230, has a function for minimizing the imbalance of the number of deletions of each block inside the flash package 230 and a block-unit capacity virtualization function, and efficiently manifests lessening of the imbalance of the number of deletions and reduction in the data storage capacity for the entire storage system 100 by having functions for calculating the number of deletions and the data occupancy of each flash package 230, and for transferring data between the flash packages 230 on the basis of the values of these number of deletions and data occupancy.