This paper presents a modeling methodology for the design of file system organizations in a local area network environment. We first propose a characterization for the workload of typical business transaction systems, and then use this measurable characterization to derive input parameters for the file distribution graph models and the queuing network models that represent two completely different file system organizations, i.e., a file server-based file system and a distributed file system. Total system throughput and mean system response time are the indices used in comparing these two design approaches. An example of this comparison is given. It is shown that this methodology and these models are useful tools for the evaluation of certain design tradeoffs.