Simulation and modeling are useful tools in prototyping advances in many areas of technology. The performance of modern processors advances much faster than that of storage components making disk systems prime candidates for simulation. Simulating disk systems allows researchers to determine and quantify the performance impact of alternative file system designs and disk data rearrangement techniques. This paper describes a System Assisted disk I/O Simulation Technique (SAST). This technique uses a real system to estimate disk request service times, relieving the researcher from the burden of modeling the target system. The system accepts disk trace data as input, and accurately predicts disk service times. In addition, we describe a disk trace collection technique capable of collecting accurate trace data from the Windows 95 operating system.

The Infrared Data Association's (lrDA) infrared data transmission protocol is a widely used mechanism for short-range wireless data communications. In order to provide flexibility for connections between devices of potentially disparate capabilities, lrDA devices negotiate the values of several transmission parameters based on the capabilities of the devices establishing the connection. This paper describes the design and implementation of a software tool, Irdaperf, to modellrDA perfonnance based on negotiated transmission parameters. Using Irdaperf, we demonstrate that for fast data rates, maximizing window size and data size are key factors for overcoming the negative effects of a relatively long link turnaround time. At slower speeds (especially 115.2 Mbps and below), these factors have a less pronounced effect.