Multi-Level Flash Memory Selective Data Storage
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Solution Overview
Problem
Traditional Multi-Level Cell (MLC) memory devices lack efficient methods to differentiate and optimize storage configurations for frequently-accessed and rarely-accessed data, leading to suboptimal average access times.
Innovation Solution
Implementing a classification system within the SSD controller to categorize data into fast-access and normal-access classes, storing frequently-accessed data in Least Significant Bit (LSB) pages and rarely-accessed data in Most Significant Bit (MSB) pages within the same MLC Flash device, allowing for flexible allocation of storage space and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If data is stored uniformly in MLC memory without differentiation, then storage capacity is maximized, but average access time increases due to mixed hot and cold data
Solution Approach 1:
The patent divides the MLC memory into two distinct storage configurations: LSB pages for fast-access (hot) data and MSB pages for normal-access (cold) data. This segmentation allows frequently accessed data to be stored in the faster LSB pages while less frequently accessed data resides in MSB pages, thereby reducing average access time without requiring entirely separate memory devices.
Solution Approach 2:
The patent applies local quality by assigning different access characteristics to different portions of the memory based on data usage patterns. Hot data stored in LSB pages enjoys fast access characteristics, while cold data in MSB pages accepts normal access characteristics. This localized optimization improves overall system performance by matching storage quality to actual data needs.
2Speed
If separate memory devices are used for fast and normal access data, then access time performance is optimized, but device complexity and cost increase
Solution Approach 1:
The patent merges the functions of separate fast-access and normal-access memory devices into a single MLC memory device by utilizing the dual-page structure (LSB and MSB pages) that inherently exists in MLC technology. This consolidation achieves the performance benefits of differentiated access speeds while avoiding the complexity and cost of maintaining separate memory devices.
Solution Approach 2:
The patent makes the MLC memory device universal by enabling it to serve dual purposes: fast-access storage for hot data and normal-access storage for cold data, all within the same physical device. This multi-functionality eliminates the need for separate specialized memory devices while maintaining optimal access performance for different data types.
3Loss of time
If all data is stored in LSB pages for fast access, then access time is reduced, but storage capacity and cost efficiency decrease
Solution Approach 1:
The patent introduces dynamic data placement that adapts to actual usage patterns. The system monitors data access characteristics and automatically places hot data in LSB pages for fast access while placing cold data in MSB pages. This dynamic approach ensures that storage capacity is efficiently utilized by matching data placement to actual access needs rather than using a static configuration.
Solution Approach 2:
The patent changes the storage parameter (access speed) based on data characteristics by storing different types of data in different pages with different access speeds. This parameter change allows the system to optimize access time for hot data while maintaining adequate capacity utilization by storing cold data in the slower but still functional MSB pages.
Data Source
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AI summary
A method for data storage includes providing a memory (32), which includes multiple groups of memory cells and is configured to concurrently store first data using a first storage configuration having a first access time, and second data using a second storage configuration having a second access time, longer than the first access time, such that each memory cell in each of the groups stores at least one bit of the first data and one or more bits of the second data. Data items are accepted for storage in the memory. The accepted data items are classified into a fast-access class and a normal-access class. The data items in the fast-access class are stored in the memory using the first storage configuration, and the data items in the normal-access class are stored in the memory using the second storage configuration.