Key Problems Analysis For Virtual File System On WAN

Based on the network and distributed technology, a model named virtual network file system(VNFS),which unites all the physical file systems into one virtual network file system to the users, is presented to research the ways of sharing and reusing the files on the wide area.The key problems in VNFS, such as system architecture, global name space, replication management and data consistency etc. will be discussed in this thesis. Some new algorithms and ideas, whose performances are analyzed and original modal is designed, will also be presented.In chapter one, I explain why we need to research VNFS and what the application environment is. In chapter two, I further analyze and summarize the actualities and disadvantage of the network file system and determine the key problems of research. In chapter three, the main research contents are described, including: designing a logical architecture which is flexible and approachable to physical network, completing GNS(Global Name Space) of VNFS, implementing a high-efficient replication management algorithms and data coherence algorithms.In chapter four, the architecture model of VNFS and the functions of every module are described. The VNFS is designed as the peer-to-peer model and every site in VNFS can play any role. In chapter five, a hierachical self-organizing overlay network model based on clustering, which is the base of VNFS logical organization, is proposed and the efficiency of this model is proved theoretically. In chapter six, the GNS of VNFS is designed based on the self-organizing overlay network model. A three layers name space, which are physical layer, logical layer and application layer, is proposed, and the relations among the three layers are presented. Using this name space we can accelerate the process of looking up a file.In chapter seven, the methods of VNFS replication management are presented, which are based on the replication management methods in distributed file systems and expand some new characteristics to fit the WAN environments. Two replication...