Simulation analysis of the IBM Subsystem Control Block architecture in a network file server environment

Advanced system bus architectures such as the Micro Channel and the EISA bus support what is called bus-mastering that allows the I/O subsystems attached to the bus to arbitrate and take control of the bus to perform data transfers independent of the system processor. I/O subsystems that can control/master the system bus are called Bus-Masters. The IBM Subsystem Control Block (SCB) architecture defines interrupt-driven as well as peer-to-peer I/O protocols for performing data transfers to/from the bus-masters. In previous studies, the performance of the SCB protocols is evaluated in network server environments using simulation models. The main drawback of these studies is that the server system is modeled in considerable detail but the network and the clients are not considered. In this study, we developed models to simulate a complete network file server environment where a single file server based on the SCB architecture provides file service to a variable number of clients on a token-ring network. We then evaluate the performance of the SCB protocols using the results obtained from the simulations.