TierStore: A Distributed Filesystem for Challenged Networks in Developing Regions

TierStore is a distributed filesystem that simplifies the development and deployment of applications in challenged network environments, such as those in developing regions. For effective support of bandwidth-constrained and intermittent connectivity, it uses the Delay Tolerant Networking store-and-forward network overlay and a publish/subscribe-based multicast replication protocol. TierStore provides a standard filesystem interface and a single-object coherence approach to conflict resolution which, when augmented with application-specific handlers, is both sufficient for many useful applications and simple to reason about for programmers. In this paper, we show how these properties enable easy adaptation and robust deployment of applications even in highly intermittent networks and demonstrate the flexibility and bandwidth savings of our prototype with initial evaluation results.