Flash Memory Controller Wear Leveling via Priority-Based Data Transfer
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Solution Overview
Problem
In flash memory systems, ineffective data remaining in physical blocks reduces storage capacity and efficiency, as updating operations take longer when effective data is transferred between blocks, leading to inefficient utilization of storage space and management challenges.
Innovation Solution
A memory controller determines data transfer between physical blocks based on a priority order, transferring static data to new blocks and keeping dynamic data in original blocks, thereby optimizing wear leveling and reducing the number of program-erase cycles, which helps in maintaining even wear and extending the life of flash memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If effective data are transferred from previous physical block to new physical block, then storage capacity is improved and ineffective data are reduced, but update operation time increases
Solution Approach 1:
The patent applies partial action by transferring only effective data (data not replaced by latest data) from the previous physical block to the new physical block, rather than transferring all data. This selective transfer reduces the data volume moved during updates, thereby decreasing update operation time while still reducing ineffective data in the flash memory system.
2Adaptability or versatility
If plural physical blocks correspond to the same logical block, then data storage flexibility is improved, but storage capacity decreases due to ineffective data
Solution Approach 1:
The patent applies discarding and recovering by identifying and discarding ineffective data (data that are replaced by latest data) while recovering and retaining only effective data in the new physical block. This selective data handling maintains the flexibility of mapping multiple physical blocks to the same logical block while minimizing the accumulation of ineffective data that would otherwise reduce storage capacity.
3Quantity of substance
If all effective data are transferred to new physical block, then ineffective data are reduced, but data transfer becomes futile when data are immediately replaced
Solution Approach 1:
The patent applies partial action by transferring only effective data (data not replaced by latest data) from the previous physical block to the new physical block, rather than transferring all data. This selective transfer reduces the data volume moved during updates, thereby decreasing update operation time while still reducing ineffective data in the flash memory system.
Data Source
AI summary
Access to flash memories is controlled so that efficiency of data writing and effective utilization of storage area go together. In the access control, priority order, for physical blocks each storing effective data, is managed so that a position of a physical block in the assignment order becomes higher according as assignment of a logical block to the physical block is performed more recently. When assigning a logical block to a free physical block, a determination is made whether a position of a previous physical block is higher than a predetermined position in the priority order. The previous physical block is a physical block, then, corresponding to the same logical block as the free physical block. When the determination is negative, effective data stored in the previous physical block is transferred to the free physical block.