FAT File System Memory Controller Serial Address Allocation
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Solution Overview
Problem
The integration of NAND flash memory with traditional FAT file systems leads to inefficiencies due to the need for frequent 'moving write' operations, which increase processing time and decrease file writing speed, especially as NAND flash memory capacity increases, and existing incremental write file systems are not compatible with FAT systems, requiring manufacturers to develop new file systems.
Innovation Solution
A memory system that incorporates a nonvolatile semiconductor memory and a controller using a FAT file system, where management data is allocated to a specific range with serial addresses, and write operations are managed using a unique logical address system that distinguishes between overwrite and incremental write logical addresses, allowing for high-speed writing by utilizing a cache block for frequent updates and restricting overwrite operations on file data blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FAT file system is used with NAND flash memory, then compatibility with existing systems is maintained, but writing speed decreases due to frequent moving write operations
Solution Approach 1:
The patent divides the storage space into two distinct regions: a first storage region for management data (FAT, directory entries) and a second storage region for file data. This segmentation allows management data to be written at high speed in the first region while file data is written in the second region, eliminating the need for moving write operations and maintaining both compatibility and performance.
Solution Approach 2:
The patent introduces a mapping table as an intermediary between logical addresses and physical addresses. The mapping table stores correspondence between logical block addresses and physical block addresses, allowing the system to translate write operations to optimal physical locations without requiring moving write operations, thus maintaining FAT compatibility while improving writing speed.
2Productivity
If management data is allocated to serial addresses in a predetermined range, then write speed is improved, but address space utilization becomes more constrained
Solution Approach 1:
The patent applies different allocation strategies to different types of data: management data is allocated to serial addresses in a predetermined range for high-speed writing, while file data is allocated using the mapping table mechanism. This local differentiation allows optimization of write speed for management data without compromising overall system functionality.
Solution Approach 2:
The patent pre-allocates a predetermined range of physical blocks for management data before actual write operations occur. This preliminary allocation ensures that management data can always be written to sequential addresses, eliminating the need for moving write operations and simplifying address space management during runtime.
3Productivity
If incremental write file system is used, then writing efficiency is improved, but compatibility with FAT system is lost and new file system development is required
Solution Approach 1:
The patent creates a universal storage management approach that works with both FAT file system and incremental write mechanisms. By using a mapping table to manage physical block allocation and separating management data from file data, the system achieves incremental write efficiency while maintaining FAT compatibility, making it universally applicable without requiring new file system development.
Data Source
AI summary
A memory system includes a nonvolatile semiconductor memory and a controller which controls the semiconductor memory, the memory system being inserted into the host device. The host device further includes a file management system which allocates a cluster defined in a FAT file system to write data and manages the data allocated to the cluster by using management data including a file allocation table defined in the FAT file system and a directory entry. The directory entry includes a root directory entry serving as entry information of a root directory of an uppermost layer and a sub-directory entry serving as entry information of a sub-directory belonging to the root directory. The file system allocates the plurality of clusters in a predetermined range in which addresses are serial to the management data.