Models of DASD subsystems: Basic model of reconnection

In this paper, devoted to modeling the performance of Direct Access Storage Devices (DASDs), a basic model of a block-multiplexor channel is developed. The goal is to properly and simply represent the missed reconnection effect together with its influence on the overall performance of a DASD subsystem. The approach taken is that of step-wise decomposition and analysis under loads of constant numbers of users. Computational algorithms for evaluating the solution obtained are considered. The use of the basic model as a building block for more complex systems is illustrated in the example of a symmetrical two-CPU system with shared disks. Finally, the limitations of the approach are discussed.