本文選題：文件系統(tǒng) + NAND��； 參考：《廣東工業(yè)大學》2012年碩士論文

【摘要】：在以往嵌入式系統(tǒng)主要在控制領域應用,在數(shù)據(jù)存儲方面的要求并不是很高。但隨著信息技術的不斷發(fā)展,嵌入式技術在諸多領域得到廣泛應用,嵌入式系統(tǒng)中要存儲的數(shù)據(jù)信息量不斷增長,對數(shù)據(jù)存儲和管理的需求越來越高,所以嵌入式文件系統(tǒng)的研發(fā)有著重大現(xiàn)實意義。 由于嵌入式設備在體積、功耗、防震等方面比較苛刻。Flash存儲器具有體積小,存儲容量大,能耗低,性價比高等特性,相比于傳統(tǒng)存儲介質,更適合在嵌入式系統(tǒng)中儲存數(shù)據(jù),已經成為是嵌入式系統(tǒng)中主要使用的存儲介質之一。目前,已經出現(xiàn)很多針對閃存的嵌入式文件系統(tǒng),但仍然存在許多的不足,包括啟動加載時間長,內存消耗多,磨損平衡不充分等。 本文針對當前NAND Flash嵌入式文件系統(tǒng)的各種不足,分別提出了優(yōu)化的方法。(1)啟動加載時間長問題。在現(xiàn)有的NAND Flash文件系統(tǒng)YAFFS中,一個塊中(block)同時存放文件屬性信息和文件數(shù)據(jù),啟動時要掃描完整個Flash中的塊。本文通過改變了文件存儲格式和管理方式,將文件屬性與文件數(shù)據(jù)存儲于不同的擦除塊,啟動加載時只掃描存儲屬性的擦除塊,從而減少啟動加載時間。(2)內存消耗大問題。因為系統(tǒng)把大量控制信息均存儲在內存中,使內存消耗大。本文借鑒程序局部性原理,僅在內存中保存最近訪問的文件信息,減少文件系統(tǒng)對內存的占用。(3)磨損平衡問題。本文通過將數(shù)據(jù)分成冷熱數(shù)據(jù)兩類,把它們交替地儲存在不同類型的空閑塊上,從而達到擦除塊間的磨損均衡。 依據(jù)上述方法,在研究現(xiàn)有YAFFS文件系統(tǒng)的基礎上,設計了一個新的NAND Flash文件系統(tǒng)—-NFFS。在測試中,NFFS啟動加載時間相比減少,內存消耗也減少,磨損更加均衡,達到了預期的效果。但是系統(tǒng)讀寫數(shù)據(jù)的速度因此受到影響,有所下降。最后把該文件系統(tǒng)應用于一個實際項目《食品安全追溯系統(tǒng)》中,以文件的形式保存交易的記錄,基本滿足項目的要求。下一步工作就是不斷改進系統(tǒng)的設計,進一步完善系統(tǒng)功能,提高系統(tǒng)的穩(wěn)定性和魯棒性。
[Abstract]:In the past, embedded system is mainly used in control field, but the requirement of data storage is not very high. However, with the continuous development of information technology, embedded technology has been widely used in many fields. The amount of data information to be stored in embedded systems is increasing, and the demand for data storage and management is increasing. So the research and development of embedded file system has great practical significance. Because embedded devices are more demanding in volume, power consumption, earthquake resistance, etc. Flash memory has the characteristics of small volume, large storage capacity, low energy consumption and high performance-to-price ratio, so it is more suitable for storing data in embedded system than in traditional storage media. It has become one of the main storage media in embedded system. At present, there are many embedded file systems for flash memory, but there are still many shortcomings, including long startup loading time, high memory consumption, insufficient wear balance and so on. Aiming at the shortcomings of the current NAND Flash embedded file system, this paper puts forward the optimization method. In the existing NAND Flash file system (YAFFS), a block is stored in a block at the same time to store the file attribute information and file data, and scan the block in the whole Flash when starting. This paper changes the file storage format and management mode, stores file attributes and file data in different erasure blocks, scans only the erasure blocks of storage attributes when starting loading, thus reduces the problem of large memory consumption. Because the system stores a large number of control information in memory, making memory consumption. Based on the principle of program locality, this paper only saves the recently accessed file information in memory, and reduces the problem of wear and tear balance between file system and memory. In this paper, we divide the data into two classes, and store them alternately on different types of free blocks, so as to achieve the wear equalization between erasure blocks. According to the above method, a new NAND Flash file system, NFFS, is designed on the basis of studying the existing YAFFS file system. In the test, the load time of NFFS is reduced, the memory consumption is reduced, the wear is more balanced, and the expected effect is achieved. But the speed at which the system reads and writes data is affected and falls. Finally, the file system is applied to a practical project called Food Safety traceability system. The record of transaction is kept in the form of files, which basically meets the requirements of the project. The next step is to improve the system design, further improve the system function, improve the stability and robustness of the system.
【學位授予單位】：廣東工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TP368.1;TP333

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