VIRTUAL FILES IN A DISTRIBUTED ENVIRONMENT.

Hierarchical naming schemes have been adopted in a number of distributed filestore designs. These schemes usually fall into one of two categories. In the first, there is a single namespace, with a fixed root, spread over all the machines in the distributed system. The user is unaware of any connection between the logical name and the physical location of a file. In the second, the total namespace is composed of some aggregation of the individual namespaces of the filestores of each component system. In this paper, it is argued that the two categories can coexist in a single distributed computer system. A scheme is described for providing highly available files, using replicated copies, within a UNIX United namespace, which is indefinitely extensible. The reliable files are accessed in exactly the same way as normal files.