Highly Available DHTs: Keeping Data Consistency After Updates

The research in the paper is motivated by building a decentralized/P2P XML storage on top of a DHT (Distributed Hash Table). The storage must provide high data availability and support updates. High data availability in a DHT can be guaranteed by data replication. However, DHTs can not provide a centralized coordination guaranteeing data consistency upon updates. In particular, replicas may have different values due to concurrent updates or partitioning of the P2P network. An approach based on versioning of replica values is presented proposing a decentralized concurrency control system, where probabilistic guarantees can be provided for retrieving a correct replica value. This paper presents the protocol as well as a statistical analysis of the lower bound of the probabilistic guarantees.

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