The advent of local-area networks has made possible the implementation of distributed file systems: file systems which physically encompass several distinct machines but which provide a global file system logically spanning the connected machines. Users who access files across this system are unaware that their files may logically reside on a machine other from their own. Distributed file systems vary widely in functionality and design, differing largely in their degree of distributed control, provisions for data consistency, and transparency.

This report describes the design and implementation of a prototype distributed file system at IBM San Jose Research Laboratory. The 925 Distributed File System (DFS925) is constructed for a network whose nodes are high-performance engineering workstations, connected by a reliable local area network. Emphasized are distributed control, the maintenance of workstation independence, and data consistency. DFS925 will be used as a research and development tool in the Computer Science Department at IBM San Jose.