Modeling and investigation of a primitive file transfer operation

The availability of high-speed networks and the reduced cost of powerful workstations have led to wide-spread use of distributed systems. File transfer is an important operation in a distributed system. It can be considered as a primitive operation in high-level applications such as file migration, process migration and load balancing. The authors develop a performance model for file transfer which consists of three submodels, one for each phase of file transfer. The read phase incorporates prefetching (read-ahead) of file blocks, the write phase incorporates postwriting (write-behind), and the control phase forces the file transfer to be sequential. The throughput of file transfer is obtained analytically using a Markov chain analysis. The validity of the model is assessed using measurement data from a Unix United system. Additional results on the performance of file transfer are also presented