Revisiting the paxos algorithm

The paxos algorithm is an efficient and highly fault-tolerant algorithm, devised by Lamport, for reaching consensus in a distributed system. Although it appears to be practical, it seems to be not widely known or understood. This paper contains a new presentation of the paxos algorithm, based on a formal decomposition into several interacting components. It also contains a correctness proof and a time performance and fault-tolerance analysis. The formal framework used for the presentation of the algorithm is provided by the Clock General Timed Automaton (Clock GTA) model. The Clock GTA provides a systematic way of describing timing-based systems in which there is a notion of “normal” timing behavior, but that do not necessarily always exhibit this “normal” timing behavior.

Authors

• Roberto De Prisco
• Butler Lampson
• Nancy Lynch Massachusetts Institute of Technology

Keywords

• I/O automata models
• Formal verification
• Distributed consensus
• Partially synchronous systems
• Fault-tolerance