Exploiting Node Connection Regularity for DHT Replication

Abstract

Distributed Hash-Tables (DHTs) provide an efficient way to store objects in large-scale peer-to-peer systems. To guarantee that objects are reliably stored, DHTs rely on replication. Several replication strategies have been proposed in the last years. The most efficient ones use predictions about the availability of nodes to reduce the number of object migrations that need to be performed: objects are preferably stored on highly available nodes. This paper proposes an alternative replication strategy. Rather than exploiting highly available nodes, we propose to leverage nodes that exhibit regularity in their connection pattern. Roughly speaking, the strategy consists in replicating each object on a set of nodes that is built in such a way that, with high probability, at any time, there are always at least $k$ nodes in the set that are available. We evaluate this replication strategy using traces of two real-world systems: eDonkey and Skype. The evaluation shows that our regularity-based replication strategy induces a systematically lower network usage than existing state of the art replication strategies.