A user-oriented synthetic workload generator that simulates user file access behavior on the basis of real workload characterizations is described. The workload generator is designed for experiments and simulations related to file system analysis. The model for this workload generator is user-oriented and job-specific, represents file I/O operations at the system call level, allows general distributions for usage measures, and assumes independence in the file I/O operation stream. The workload generator consists of three parts that handle specification of distributions, creation of an initial file system, and selection and execution file I/O operations. Results from experiments on a network file system (NFS) verify that the workload generator can produce realistic workloads and demonstrate the application of the generator.