Replication in Ficus distributed file systems

Ficus is a replicated general filing environment for Unix intended to scale to very large (nationwide) networks. The system uses an optimistic one copy availability model in which conflicting updates to the file system´s directory information are automatically reconciled, while conflicting file updates are reliably detected and reported. The system architecture is based on a stackable layers methodology which permits a high degree of modularity and extensibility of file system services. The motivations for replication are presented, and the case for optimistic concurrency control for large-scale distributed file systems is summarized. A brief description of the Ficus file system is presented and a number of outstanding issues which must be addressed are outlined