File-oriented Distributed System And Automatic Load Balance

With the developing of LAN technology , more and more Local Area Networks are set up. A study has been made about the problems appearing in the net . Through the Analysis of the user access characteristics in the net , the "File Burst Access, FBA" and the "Server Tide Access, STA" characteristics are discovered .Based on these two characteristics and some existing technology , a File-Oriented distributed system "DFTP" model is built to solve the problems in the LANs. This system is built upon the application level , it is transparent to the end users. The whole system appears like a huge storage server to provide service.In a distributed system, load balance is the first thing that need to be considered. The DFTP system is designed to use in a file download environment, so the load balance is File-Oriented too. DFTP system provides two methods to achieve file balance, "Dynamic File Balance, DFB" and "Forecast File Balance, FFB". With the balance of file, the load of the system will be balanced.The File-Oriented characteristic decide the DFTP system is mainly used in LAN. In the procedure of file balance, files will be transmitted between storage servers, but nowadays, it is difficult to achieve high speed transfer in Internetarea.To manage the redundancy files and provide a way to verify transferred files, DFTP use a Message-Digest Algorithm 5 to assign characteristic code to files. The characteristic code is the primary evidence to manage files in DFTP system. The "Copy Attenuation" is also used to delete the redundancy files that are made in the file balance procedure, to avoid the waste of storage resources.The experiment data appears that the DFTP system can solve the problems of the LAN in a certain extent. The DFTP system is also conductively to build File-Oriented distributed system in Internet area.