Probabilistic quorum systems

We initiate the study of probabilistic quorum systems, a technique for providing consistency of replicated data with high levels of assurance despite the failure of data servers. We show that this technique offers effective load reduction on servers and high availability. We explore probabilistic quorum systems both for services tolerant of benign server failures and for services tolerant of arbitrary (Byzantine) ones. We also prove bounds on the server load that ca be achieved with these techniques. (C) 2001 Academic Press.