Flash Memory Cache Block Management for Wear Leveling
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Solution Overview
Problem
Flash memory systems face inefficiencies in data management, leading to reduced storage capacity and accelerated memory element degradation due to frequent write-back operations and garbage collection, which shorten the service life and decrease write performance.
Innovation Solution
A memory apparatus and control method that utilize a cache block arrangement to minimize write-back operations by writing data to new cache blocks when exceeding or falling short of designated logical boundaries, and prioritizing write-backs based on data update frequency, thereby reducing garbage collection and extending the service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is written to the same physical block repeatedly, then storage capacity is utilized efficiently, but memory element degradation accelerates due to repeated updates
Solution Approach 1:
The patent segments the flash memory into multiple blocks and implements a wear-leveling mechanism that distributes write operations across different blocks. When a block reaches its update limit, the system transitions to page-level updates within that block, effectively segmenting the update strategy by block status. This segmentation allows efficient storage utilization while preventing any single block from degrading too quickly.
Solution Approach 2:
The patent changes the update parameter from block-level to page-level based on the block's update count. When a block's update count exceeds a threshold, the system switches from writing entire blocks to updating only the specific pages that need changes. This parameter change enables continued storage utilization while reducing the degradation impact on individual blocks.
2Stability of the object's composition
If entire physical blocks are updated even for small data changes, then data integrity is maintained, but access time increases and memory element degradation is promoted
Solution Approach 1:
Instead of updating entire blocks for every data change, the patent implements partial updates at the page level. When data needs to be updated, only the specific pages containing the changed data are modified, rather than rewriting the entire block. This partial action maintains data integrity for updated pages while significantly reducing access time and avoiding unnecessary updates to unchanged data.
Solution Approach 2:
The patent performs preliminary checks to determine which pages within a block actually need updating before executing the write operation. By identifying and updating only the necessary pages in advance, the system maintains data integrity where needed while avoiding unnecessary full-block updates that would increase access time and cause degradation.
3Ease of operation
If header areas, link information areas, and flag areas are provided in each block, then data management is facilitated, but effective storage capacity decreases
Solution Approach 1:
The patent extracts the management information (headers, link information, flags) from being embedded in every block and consolidates it into a separate management area. This extraction allows the majority of blocks to be used purely for data storage without overhead, significantly increasing effective storage capacity while maintaining data management capabilities through the centralized management structure.
Solution Approach 2:
The patent creates a universal management area that serves all blocks in the flash memory system. Instead of duplicating management structures in each block, a single management area provides block allocation, wear-leveling tracking, and update status information for the entire memory, enabling efficient data management across all blocks while maximizing storage capacity.
4Stability of the object's composition
If write-back operations are performed frequently to maintain cache consistency, then data consistency is ensured, but write performance decreases due to garbage collection
Solution Approach 1:
The patent treats cache blocks as disposable temporary storage that can be overwritten without expensive garbage collection. By allowing cache blocks to be invalidated and replaced rather than meticulously managed, the system ensures data consistency through the logical-to-physical address mapping while avoiding the performance penalty of frequent garbage collection operations.
Solution Approach 2:
The patent introduces an intermediary address mapping layer (logical-to-physical conversion table) that decouples the cache management from the physical block management. This intermediary allows write-back operations to proceed efficiently by translating logical addresses to physical locations without requiring immediate garbage collection, thereby maintaining data consistency while preserving write performance.
Data Source
AI summary
A memory control method is disclosed which includes: a storing step of storing a logical to physical conversion table retaining relations of correspondence between addresses of logical blocks in a user data area on the one hand, and addresses of physical blocks assigned to the logical blocks on the other hand, along with addresses of physical blocks in a cache area, the physical block addresses corresponding to the physical block addresses in the logical to physical conversion table; a first writing step of writing, to a deleted new cache block in the cache area, data in excess of a designated logical boundary which defines a logical space size in units of a plurality of sectors within a user data block of the user data area; and a second writing step of writing the data starting from the beginning of the new cache block upon data write in the first writing step to the new cache block, regardless of the logical address space of the new cache block.