xFS: A Wide Area Mass Storage File System

The current generation of le systems are inadequate in facing the new technological challenges of wide area networks and massive storage. xFS is a prototype le system we are developing to explore the issues brought about by these technological advances. xFS adapts many of the techniques used in the eld of high performance multiprocessor design. It organizes hosts into a hierarchical structure so locality within clusters of workstations can be better exploited. By using an invalidation-based write back cache coherence protocol, xFS minimizes network usage. It exploits the le system naming structure to reduce cache coherence state. xFS also integrates di erent storage technologies in a uniform manner. Due to its intelligent use of local hosts and local storage, we expect xFS to achieve better performance and availability than current generation network le systems run in the wide area.