Flash Memory Data Mapping Table Segmentation for Cache Optimization
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Solution Overview
Problem
Flash memory devices face challenges in managing large memory spaces for data mapping tables, leading to inefficiencies in random access memory usage due to the need for effective data maintenance methods.
Innovation Solution
A data storage device with a flash memory and random access memory that employs a cache area, sequential-order table, and reverse-order table to efficiently manage data mapping sets, using a cache-area mapping table to record set indexes and update the order of data access, thereby optimizing memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a data mapping table is used to record mapping relationships between logical and physical addresses in flash memory, then data access efficiency is improved, but the memory space required in random access memory increases significantly
Solution Approach 1:
The patent divides the data mapping table into multiple data mapping sets, where each set contains a portion of the mapping relationships. Only the necessary data mapping sets are loaded into the cache area at any given time, rather than loading the entire mapping table. This segmentation allows the system to maintain fast access to mapping data while significantly reducing the memory space required in random access memory.
Solution Approach 2:
The patent loads required data mapping sets into the cache area in advance before they are needed for data access operations. By pre-loading the mapping sets that will be needed soon, the system ensures that when data access requests occur, the mapping information is already available in the cache, maintaining high access efficiency while avoiding the need to keep all mapping data in memory simultaneously.
2Speed
If the entire data mapping table is loaded into the cache area, then data access speed is maximized, but the cache area size must be very large
Solution Approach 1:
The data mapping table is segmented into multiple data mapping sets that can be independently managed. The cache area only needs to accommodate the currently required mapping sets rather than the entire mapping table. This segmentation enables the system to achieve fast data access with a much smaller cache area by loading only the necessary portions of the mapping table into cache.
Solution Approach 2:
The patent implements dynamic loading and replacement of data mapping sets in the cache area based on access patterns and requirements. When the cache area is full, less frequently accessed mapping sets are replaced with newly required ones. This dynamic management allows the system to maintain optimal data access speed while adapting to changing access patterns without requiring a permanently large cache area.
3Quantity of substance
If data mapping sets are frequently loaded and replaced in the cache area, then memory usage is optimized, but the complexity of data maintenance increases
Solution Approach 1:
The patent employs a reference counting mechanism that provides feedback on the usage status of data mapping sets. When a data mapping set is accessed, its reference count is updated, and this information is used to determine whether to keep the mapping set in the cache or replace it. This feedback-based approach automates the decision-making process for cache management, reducing the complexity of manual data maintenance while optimizing memory usage.
Solution Approach 2:
The system automatically manages the loading and replacement of data mapping sets in the cache area based on predefined criteria and access patterns, without requiring complex external control. The cache management mechanism serves itself by monitoring its own state and making appropriate loading/replacement decisions, which simplifies the overall data maintenance complexity while achieving efficient memory usage.
Data Source
AI summary
The present invention provides a data storage device including a flash memory and a random access memory. The flash memory has a data mapping table arranged to record a plurality of mapping relationships between the logical addresses and the physical addresses of a plurality of pages of the flash memory. The data mapping table is divided into a plurality of data mapping sets. The random access memory has a cache area, a sequential-order table, a reverse-order table and a cache-area mapping table. The cache area stores part of the data mapping sets. The cache-area mapping table records the set indexes of the data mapping sets of the cache area. The sequential-order table records the order that the data mapping sets are read from the cache area. The reverse-order table records the opposite order that the data mapping sets are read from the cache area.