PDL Abstract

Egalitarian Paxos

Carnegie Mellon University Parallel Data Lab Technical Report CMU-PDL-12-108. July 2012.

Iulian Moraru1, David G. Andersen1, Michael Kaminsky2

1Carnegie Mellon University
2 Intel Labs

This paper describes the design and implementation of Egalitarian Paxos (EPaxos), a new distributed consensus algorithm based on Paxos. EPaxos achieves two goals: (1) availability without interruption as long as a simple majority of replicas are reachable—its availability is not interrupted when replicas crash or fail to respond; and (2) uniform load balancing across all replicas—no replicas experience higher load because they have special roles. Egalitarian Paxos is to our knowledge the first distributed consensus protocol to achieve both of these goals efficiently: requiring only a simple majority of replicas to be non-faulty, using a number of messages linear in the number of replicas to choose a command, and committing commands after just one communication round (one round trip) in the common case or after at most two rounds in any case. We prove Egalitarian Paxos's properties theoretically and demonstrate its advantages empirically.

KEYWORDS: Distributed Consensus, Paxos

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