VISA - NETSTATIONS VIRTUAL INTERNET SCSI ADAPTER

In this paper we describe the implementation of VISA, our Virtual Inte rnet SCSI Adapter. VISA was built to evaluate the performance impact o n the host operating system of using IP to communicate with peripheral s, especially storage devices. We have built and benchmarked file syst ems on VISA-attached emulated disk drives using UDP/IP. By using IF, w e expect to take advantage of its scaling characteristics and support for heterogeneous media to build large, long-lived systems. Detailed f ile system and network CPU utilization and performance data indicate t hat it is possible for UDP/IP to reach more than 80% of SCSI's maximum throughput without the use of network coprocessors. We conclude that IP is a viable alternative to special-purpose storage network protocol s, and presents numerous advantages.