Wayfinder

The decreasing costs of computing devices, increases in connectivity, and improved performance are altering the computing environments of users in fundamental ways. Users are no longer restricted to operating single devices in isolation but rather distribute and accessinformation across many devices and develop complex sharing patterns among groups of users. Unfortunately, while these trends are significantly enriching the user's computing experience, they are also increasing the data management overhead as users must explicitlyreason about data placement and replication across multiple devices and logical sharing groups.In this thesis, we present the Wayfinder file system, which was designed to simplify the management of information in federate systems. Wayfinder focuses on three critical management deficiencies present in most current federated environments: 1) the lack of a consistent view for stored information across devices, 2) the required manual management of replicated information, and 3) the limited search/ranking capability for finding relevant information.The Wayfinder file system addresses these deficiencies by providing three synergistic abstractions: 1) a global namespace that is uniformly accessible across connected and disconnected operation, 2) a user-centric automatic availability management to ensure continuous access to information based on data-centric availability policies, and 3) a multi-dimensional fuzzy search framework that significantlyimproves relevance ranking. We will show that these abstractions simplify the management burden by requiring users to reason only about the data and its properties while ignoring the underlying physicalcomplexities of the system.Underlying all three abstractions is a common implementation layer that adheres to three principles. First, any subset of nodes in a Wayfinder community can interact normally when they are interconnected, regardless of the membership of the subset. Second,all protocols and interactions are tolerant of a weakly consistent model allowing them to suffer unexpected devices departures. Finally, devices are assumed to be owned by specific users and so should prioritize the needs of their owners in the presence of resourceconstraints, while using excess resources to benefit the community as a whole.