Disconnected Operation for AFS

AFS plays a prominent role in our plans for a mobile workstation. The AFS client manages a cache of the most recently used files and directories. But even when the cache is hot, access to cached data frequently involves some communication with one or more file servers to maintain consistency guarantees. Without network access, cached data is soon rendered unavailable.

We have modified the AFS cache manager to offer optimistic consistency guarantees when it can not communicate with a file server. When the client reestablishes a connection with the file server, it tries to propagate all file modifications to the server. If conflicts are detected, the replay agent notifies the user that manual resolution is needed.

Our system brings the benefits of contemporary distributed computing environments to mobile laptops, offering a fresh look at the potential for nomadic computing.