We consider the problem of ensuring high data availability in federated content sharing systems. Ideally, such a system would provide high data availability in a device transparent manner so that users are not faced with the timeconsuming and error-prone task of managing data replicas across the constituent devices of the system. We propose a novel unified availability model and a decentralized replication algorithm to approximate this ideal. Our availability model addresses three different concerns: availability during connected operation (online), availability during disconnected operation (offline), and availability after permanent disconnection from the federated system (ownership). Our replication algorithm centers around the intuition that devices should selfishly use their local storage to ensure offline and ownership availability for their individual owners. Excess storage, however, is used communally to ensure high online availability for all shared content. Evaluation of...
Christopher Peery, Thu D. Nguyen, Francisco Matias