File system design using large memories

It is shown using experimental data that file activity is fairly stable over time, and the implications of this finding for file system design are examined. Several file access patterns and how they may be exploited to improve file system performance are shown. In particular, it is shown that current file temperature can be used to predict future file temperature. The design of the iPcress file system, which uses both a large disk cache and other techniques to improve file system performance is outlined. iPcress has a variety of cache staging algorithms and can choose the one most appropriate for each file. iPcress also stores access histories for each file to guide decisions such as file layout on DASD and caching. Preliminary performance figures for iPcress are presented.<>