In this paper we present a dynamic file caching strategy that improves the average job response time while maintaining file consistency. By making the assumption that the read/write ratio of each file is fixed throughout the system, this strategy reduces to a simple criterion that can be applied using only local information for making caching decisions. In the second half of the paper, we present a set of simulation experiments that we conducted in order to evaluate the performance of this algorithm compared to the simple caching strategies of always caching and never caching files, in various network configurations.