【作者】 孙莉娜；

【导师】 金志刚；

【作者基本信息】 天津大学 ， 计算机应用技术， 2006， 硕士

【摘要】 随着在线数据的快速增长,传统的服务器成为网络服务的瓶颈。网格技术在高性能的存储技术领域发挥着巨大的作用。然而,Data Grid的面向广域网的数据管理解决方案还是无法满足海量用户的海量存储要求,因此,基于网络的分布式文件系统的有效性进一步体现了出来。NFS是最早的实现网络文件共享的文件系统,不保存系统间的状态信息是NFS的一个重要特性,主要应用于小型局域网上。AFS则是一个能够扩展到几千个用户的分布式文件系统,它是第一个在客户端采用永久缓冲策略的文件系统,但AFS没有解决分布式数据或者其他大型随机访问文件的需要,也没有处理数据的不一致问题。DFS是Windows 2000(Server版)/2003系统自带的一项文件服务。在客户端,DFS对AFS进行了改造,主要差别在于使用优秀的文件颗粒共享。而Coda是最早支持断连接操作的分布式文件系统,它的前身是AFS文件系统,适合在网络连接没有保障的环境中使用。由于Coda没有有效地向用户报告错误信息,用户常常不知道问题在哪里。作者在此基础上给出了改进的框架——名为Coda操作台的图形接口综述,使得弱连接或断连接情况时缓存对用户半透明,这样Coda的可用性就提高了,用户也能够很好地理解系统的行为。同时,作者给出了具体的实现方案和改进后的效果。更多还原

【Abstract】 Along with on line data fast growth, the traditional server becomes the network service bottleneck. The grid technology is playing the huge role in the high performance memory area of technology. However, Data Grid, the data management solution for WAN, is unable to satisfy the mass memory request for the magnanimous user. Therefore, network-based distributed file system validity has further demonstrated out.NFS is the earliest file system realizing network document sharing. Non-keeping system among state information is an important characteristics of NFS. It mainly applies on the small LAN. AFS then can expand to several thousand user’s distributed file system. It is the first file system that uses the permanent buffer strategy in the client side. But AFS has not solved distributional data or other documents required large random, also has not processed the inconsistent of the data. DFS is an item of file service which Windows 2000(Server version)/2003 system. In the client side, DFS has carried on the transformation to AFS, the main difference lies in the use of outstanding document pellet to share. While Coda is the first distributed file system which supports disconnected operation. The ancestor of Coda is the AFS distributed file system, it is suitable for the environment in which the network connection is not stable.Coda does not effectively tell user what is wrong with it. The author present the improvement frame in this foundation——an overview of graphical interface called the CodaConsole,that makes caching translucent to Coda users in the presence of disconnected or weakly connected operation. Hence the availability of Coda is improved greatly. The user also can understand system behavior well. At the same time, the author has produced the concrete realization plan and the improvement effect.更多还原