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题名	面向高清媒体的嵌入式存储系统 MSFS 关键技术的研究
作者	吴丽彬
学位类别	博士
答辩日期	2009-05-25
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	高清 媒体 嵌入式 M结构文件系统 可靠性 存储结构 存储安全 可信恢复 快速检索 预读策略
其他题名	Research on Key Technologies of MSFS — An Embedded File Storage System for HD Media File
学位专业	信号与信息处理
中文摘要	媒体产业逐步进入数字化高清时代，媒体的高清数字化同时也带来了更大的存储数据量的压力。其使得目前的嵌入式存储系统暴露出性能、可靠性等方面的诸多问题，对嵌入式系统的数字存储技术提出更高的要求。基于上述应用背景，本文结合高清媒体文件在嵌入式存储方面的具体需求，研究针对高清媒体的嵌入式存储技术，提出一种面向高清媒体文件的嵌入式系统的（M_Structure File System, MSFS) M结构嵌入式系统存储解决方案，提高了嵌入式系统的高清晰度媒体内容存储性能、稳定性、可靠性，对实现高清媒体的高性能嵌入式存储，保证嵌入式存储系统的存储可靠性，具有重要的研究意义。 本文主要贡献如下： (1)存储结构方面(MStructure) 提出了基于链式动态扩展的嵌入式系统媒体数据存储结构（MStructure）。该方向通过在数据存储结构方面的全新设计，实现适合高清媒体文件存储的最优结构。这种最优结构存储模型不仅能够降低系统崩溃概率与文件丢失概率，同时还可通过降低I/O操作频率，达到降低磁头寻址时间，提高存储系统读写性能的目的。 (2)数据存储安全方面(MSnap) 提出了一种安全的动态自适应数据存储安全策略模型(MSnap)。该模型基于结构集与任务集的元数据写入模式识别模型，抽象安全级别划分模型以及策略模型，为数据安全存储建立了通用架构模型，使情况复杂、数据类型繁多、处理策略较多的存储安全策略建立在统一的架构模型内，达到结构清晰、任务明确的目的。同时能够有效提高从系统崩溃与文件丢失等错误中重新恢复的概率，为可信恢复策略模型提供了取证与恢复的依据。 (3)可信恢复策略方面(MRecovery) 提出了基于可信恢复策略模型的元数据恢复机制（MRecovery）。该方向中包含了对日志、快照、现有元数据的全面分析，并提供问题反推模型，为元数据恢复提供可信概率与小型知识库。其是一种低开销的快速校验、快速恢复技术，所需时间与内存等系统开销均低于Ext2与Ext3文件系统的FSCK技术，适用于高清媒体的嵌入式存储系统。 (4)数据检索方面(MSearching) 提出了基于哈希预处理模型的快速文件检索算法(MSearching)。该方向主要通过哈希预处理算法来加速对文件的检索，并通过引入字节趋势值的概念以及其他剪枝条件，对哈希冲突进行有效剪枝，降低了对目录索引的反复反向追踪频率，有效提高文件的检索速度。 (5)I/O性能方面(MI/O) 提出了一种能够提高该存储系统随机读操作I/O效率的预读算法。MI/O方向的重点在于解决文件系统随机读取效率问题。其通过引入热点文件元数据缓存、元数据缓存压缩技术，降低文件系统对元数据区的访问频率，从而避免磁头的反复移动，降低了I/O操作频率，有效保证元数据的可靠性。 本文最后对MSFS嵌入式存储系统进行性能与可靠性等多个方面的测试，并同当前嵌入式系统中常用的文件系统进行对比，详细分析MSFS系统的优势和目前存在的不足，指
英文摘要	Nowadays, the media industry begins to enter the hi-definition of digitalization times.Although the media has some new features such as hi-definition, hi-precision, digitalization andbig capacity, it also brought great pressure on data storage and make the embedded storage system exposed some performance, reliability and other problems at the same time. Therefore,the higher requirements will be proposed for digital storage technique based on embedded system.According to this background of application, and combining with engineering practice, this paper analyzes and concludes practical problems, and then puts forward a complete solution which is the M Structure File System (MSFS) — an embedded file storage system for HD media sfile. We have implemented MSFS prototype and analyzed its performance. The Preliminary results are presented at the last section of this paper show that this scheme can improve the storage performance，stability and reliability. Implementing this Scheme and guarantee the reliability of this embedded file storage system has positive research significance. The main contributions of this paper are as follows: (1) Storage structure (MStructure) The chained and dynamic expansion storage structure of embedded HD media file storage system is proposed. The strategy re-designs the data storage structure to achieve the optimal storage structure for HD media file storage. The optimal structure model not only can reduce the probability of system collapse and loss of file, but also can decrease the time of head addressing by reduce the I/O operating frequency. It improves the reading and writing performance of this embedded file storage system for HD media. (2) Data storage security (MSnap) A dynamic adaptive data storage security strategy model is proposed for data recovery model. In this model, the identification model of meta-data write mode based on data structure set and task set, and the abstract model of security level are the key sub-model of data storage security strategy. The strategy designs a common framework for Data Security storage, and makes the complex situation, different data types and more processing strategies of data security storage establishing in a unified framework model. It can provide the evidence for MRecovery, and increase the probability of recovery from the loss of file and system collapse. (3) Trusted recovery strategy (MRecovery) A model-based trusted restoring strategy of the system recovery mechanism is put forward for file system reliability and stability. This strategy includes the structural model, processing model, and backward fuzzy reasoning model of trusted restoring strategy. According to the MSnap’s valid nodes, MRecovery is a fast checking and restoring strategy base on valid nodes. It is a low system overhead requirement strategy for embedded storage system recovery. (4) Fast file searching (MSearching) The hash-based pre-processing model of fast file searching algorithm is proposed to improve the file searching speed by using the hash table of directory entry index. This algorithm also introduces the trend value of file name bytes and other pruned conditions to decrease the backward tracing frequency of directory entry index and probability of hash collisions. (5) I/O performance (MI/O) The pre-fetching algorithm is proposed for the I/O efficiency improvement of random read operation. To enhance the I/O efficiency of random read operation, the use of key technologies includes the establishment of hot files’ index table, the caching of important index data, and thepre-fetching of file data. This strategy is beneficial to reduce the frequency of data accessing, andensure the reliability of metadata. In the last section, this paper gives the experimental results and evaluates the performance,reliability and other aspects of this embedded file storage system for HD media (MSFS). Comparing with the traditional and common file system based on embedded system, it also analyzes the advantages and disadvantages of MSFS in detail. At the end of this article, the summarizing of the contributions and further research work are proposed.
语种	中文
公开日期	2011-05-07
页码	175
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/480]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	吴丽彬. 面向高清媒体的嵌入式存储系统 MSFS 关键技术的研究[D]. 声学研究所. 中国科学院声学研究所. 2009.

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