Real-time UNIX application filestores

From the inception of real-time computing, there has been concern about the performance of disk I/O, especially as it relates to application filestores such as those running under variants of the UNIX operating system. We present a brief discussion of UNIX filestores and show how one can easily bound the number of physical file I/Os that the UNIX operating system must perform to execute a given application process. Using the established bound for the number of physical disk I/Os, one can develop close analytical approximations of application processes elapsed running time which is of critical importance for real-time applications.