| Over the last decade, improvement in processor performance has outpaced the performance improvement in the disk subsystem. Therefore, the performance of many computers is paced by the performance of the disk system. Disk systems have been developed as an autonomous subsystem that meets the required performance by using architectural alternatives such as the multipath, disk buffer and disk interleaving. Traditionally, disk I/O systems have been designed by adhoc manual methods with little help from computer aids that do not permit the design and evaluation of more than a few design alternatives.;This dissertation presents a systematic design method and the development of a design aid that should improve the heuristics for disk I/O system design. The design aid is an integrated environment for menu-driven interactive design supported with a design taxonomy, performance analysis, and design guide using a frame-based common knowledge base of disk I/O system information. The aid formulates the design taxonomy into menus through which the design progresses. Performance analysis is accomplished by a library of analytic and discrete event simulation models implemented in Lisp with list structure and object-oriented operations. Each candidate design is guided by an expert system that gives advice to the designer for design modification that will improve the performance. To support the systematic approach taken in this research, performance models and design heuristics for the various architectural alternatives have been developed that have not previously been described. |
