Cluster based architectures that employ high performance inexpensive Personal Computers (pcs) interconnected by high speed commodity interconnect have been recognized as a cost-effective way of building high performance scalable Multimedia-On-Demand (mod)storage servers [4, 5, 7, 9]. Typically, the pcs in these architectures run operating systems such as unix that have traditionally been optimized for interactive computing. They do not provide fast disk-tonetwork data paths and guaranteed cpu and storage access. This paper reports enhancements to the 4.4 bsd unix system carried out to rectify these limitations in the context of our Project Massively-parallel And Real-time Storage (MARS) [7]. We have proposed and implemented the following enhancements to a 4.4 bsd compliant public domain NetBSD unix operating system: (1) A new kernel buffer management system called Multimedia M-buf (mmbuf) which shortens the data path from a storage device to network interface, (2) priority queueing..
