FAT2 Cluster Management Table for File Access Efficiency
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Solution Overview
Problem
The complexity of file access processes increases with the need to support various FAT formats, leading to increased maintenance hours and decreased access efficiency due to larger FAT entry sizes, which reduces the cache hit rate and search efficiency.
Innovation Solution
A method for file access that uses a cluster management table with a first table indicating continuous addresses and a second table providing cluster identification information for discontinuous addresses, allowing for unified file access across different FAT formats by converting FAT entries into a smaller FAT2 format with a discontinuous cluster list.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the FAT entry size is increased to support larger recording mediums, then the controllable maximum size of the recording medium increases, but the cache hit rate decreases and access efficiency deteriorates
Solution Approach 1:
The patent segments the FAT entry into two separate components: a FAT table containing only continuous cluster information (2 bytes per entry) and a discontinuous cluster list containing discontinuous cluster information. This segmentation allows the main FAT table to remain small and cache-friendly while the discontinuous cluster list handles the additional addressing capability needed for larger recording mediums.
Solution Approach 2:
The patent introduces a discontinuous cluster list as an intermediary data structure that mediates between the limited FAT entry size and the need to address clusters on larger recording mediums. This intermediary stores the mapping between cluster numbers and their actual physical locations, allowing the system to support larger capacities without increasing the base FAT entry size.
2Adaptability or versatility
If the FAT entry size is increased to support various FAT formats, then the maximum recording medium capacity increases, but the maintenance hours increase and access efficiency decreases
Solution Approach 1:
The patent creates a universal file access program that can handle all FAT formats (FAT12, FAT16, FAT32, exFAT) through a single implementation. The unified interface using the FAT table and discontinuous cluster list structure allows the same access logic to work across different FAT variants, eliminating the need for separate maintenance of multiple format-specific code paths.
3Adaptability or versatility
If the FAT entry size is increased, then the controllable cluster number increases, but the cache hit rate decreases
Solution Approach 1:
The patent segments cluster addressing information into two parts: continuous cluster addresses stored in the compact FAT table (2 bytes per entry) that fits in cache, and discontinuous cluster addresses stored in the separate discontinuous cluster list. This segmentation ensures that the frequently accessed FAT table remains small and cache-resident, maintaining high cache hit rates while still supporting large numbers of clusters through the extended discontinuous cluster list.
Data Source
AI summary
A method for file access includes accessing, by a processor, a file which is divided and stored in data area including a plurality of access units on the base of an access unit management table, the accessing including using a first table included in the access unit management table, the first table including a first management information corresponding to a first access unit and indicating that the first access unit and a second access unit following the first access unit in chains are located in continuous addresses and a second management information corresponding to the first access unit and indicating that the first access unit and the second access unit are located in discontinuous addresses, and using a second table included in the access unit management table, the second table including access unit identification information of the first and the second access units which are located in the discontinuous addresses.