面向多媒体存储的FAT文件系统研究与应用
发布时间：2018-08-31 20:28
【摘要】：随着技术的发展，，音视频相关的应用逐渐普及，类似行车记录仪的便携式多媒体存储系统更多的深入人们的生活。便携式嵌入式设备多使用SD卡、U盘等可移动存储设备，以方便与PC机交换数据。由于FAT文件系统在各个操作系统上良好的兼容性，目前大多数便携式嵌入式设备均使用FAT文件系统来存储数据。 但是，FAT文件系统在进行音视频多媒体存储特别是多路并发存储时，会产生严重的碎片，影响读写性能。多媒体文件通常具有很大数据量，容易形成文件碎片。在并发存储情况下，顺序查找空闲簇并分配的策略使得不同文件的数据簇交织存储，恶化了文件碎片情况。FAT文件系统的另一不足是对FAT表的严重依赖，文件的读写过程中对FAT表频繁访问的IO开销一定程度上影响了读写效率。 多媒体文件存储与传统文本存储不同，它具有一次写入多次读取，顺序访问，大数据量等特点，而FAT文件系统作为一种通用文件系统并不能很好地适应这些特点。本文将结合多媒体文件的存储特性，在保持兼容性的前提下对FAT文件系统进行改进，使之更适合多媒体的存储。改进工作包含两个方面，一方面是在内存中建立FAT表的位图索引完成空闲簇的搜索，以便减少系统IO负荷；另一方面是在位图索引基础上，提出一种基于簇组的可变大小块分配机制，用于扩展空闲块分配单元大小。论文通过测试表明，以上改进提升了FAT文件系统在多路并发存储条件下对于大文件的读写性能。
[Abstract]:With the development of technology, the application of audio and video is becoming more and more popular, and the portable multimedia storage system similar to CarLog goes deeper into people's life. Portable embedded devices use SD card, U disk and other removable storage devices to facilitate the exchange of data with PC. Because of the good compatibility of FAT file system in various operating systems, most portable embedded devices use FAT file system to store data. However, in the audio and video multimedia storage, especially in the multi-channel concurrent storage, the fat file system will produce serious fragments, which will affect the performance of reading and writing. Multimedia files usually have a large amount of data, easy to form file fragments. In the case of concurrent storage, the strategy of searching idle clusters sequentially and allocating them makes the data clusters of different files interleaved and stored, which exacerbates the file fragmentation. Fat file system is heavily dependent on FAT tables. The IO overhead of frequent access to FAT tables in the process of reading and writing of files affects the efficiency of reading and writing to a certain extent. The multimedia file storage is different from the traditional text storage. It has the characteristics of one write multiple read, order access, large amount of data, etc. As a general file system, FAT file system can not adapt to these characteristics. In this paper, we will improve the FAT file system on the premise of keeping compatibility with the storage characteristics of multimedia files to make it more suitable for multimedia storage. The improvement includes two aspects: on the one hand, building the bitmap index of FAT table in memory to complete the search of free cluster, in order to reduce the system IO load; on the other hand, on the basis of bitmap index, A variable size block allocation mechanism based on cluster group is proposed to extend the size of free block allocation unit. The test results show that the above improvements can improve the read and write performance of FAT file system for large files under the condition of multi-channel concurrent storage.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333
本文编号：2216072
[Abstract]:With the development of technology, the application of audio and video is becoming more and more popular, and the portable multimedia storage system similar to CarLog goes deeper into people's life. Portable embedded devices use SD card, U disk and other removable storage devices to facilitate the exchange of data with PC. Because of the good compatibility of FAT file system in various operating systems, most portable embedded devices use FAT file system to store data. However, in the audio and video multimedia storage, especially in the multi-channel concurrent storage, the fat file system will produce serious fragments, which will affect the performance of reading and writing. Multimedia files usually have a large amount of data, easy to form file fragments. In the case of concurrent storage, the strategy of searching idle clusters sequentially and allocating them makes the data clusters of different files interleaved and stored, which exacerbates the file fragmentation. Fat file system is heavily dependent on FAT tables. The IO overhead of frequent access to FAT tables in the process of reading and writing of files affects the efficiency of reading and writing to a certain extent. The multimedia file storage is different from the traditional text storage. It has the characteristics of one write multiple read, order access, large amount of data, etc. As a general file system, FAT file system can not adapt to these characteristics. In this paper, we will improve the FAT file system on the premise of keeping compatibility with the storage characteristics of multimedia files to make it more suitable for multimedia storage. The improvement includes two aspects: on the one hand, building the bitmap index of FAT table in memory to complete the search of free cluster, in order to reduce the system IO load; on the other hand, on the basis of bitmap index, A variable size block allocation mechanism based on cluster group is proposed to extend the size of free block allocation unit. The test results show that the above improvements can improve the read and write performance of FAT file system for large files under the condition of multi-channel concurrent storage.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP333
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