Study of the I/O Request Response Time in Network Storage Systems

Although the network storage technology has decreased the disadvantage of traditional storage systems based on host directed access storage, the introduction of the network layer has a strong impact on the average response time of I/O request and makes performance difficult to evaluate. In this paper, the process for two common network storage architectures, NAS （network attached storage） and SAN （storage area network）, is discussed. Moreover, the evaluation model for network storage is presented. In the experiment it is found that the value that the model predicts is close to the data. The result of both the model and experiment shows that the performance of network is related not only to the physical character of the storage and network devices, but also to the workload. Moreover, the workload has less impacts on the performance of the fibre channel than on that of the TCP/IP network. Fibre channel has better performance only for I/O response rate.