Paxos Quorum Leases

Abstract

This paper describes quorum leases, a new technique that allows Paxos-based systems to perform reads with high throughput and low latency. Quorum leases do not sacrifice consistency and have only a small impact on system availability and write latency. Quorum leases allow a majority of replicas to perform strongly consistent local reads, which substantially reduces read latency at those replicas (e.g., by two orders of magnitude in wide-area scenarios). Previous techniques for performing local reads in Paxos systems either (a) sacrifice consistency; (b) allow only one replica to read locally; or (c) decrease the availability of the system and increase the latency of all updates by requiring all replicas to be notified synchronously. We describe the design of quorum leases and evaluate their benefits compared to previous approaches through an implementation running in five geo-distributed Amazon EC2 datacenters.

Asynchronous Consensus Quorum Read: Pioneering Read Optimization for Asynchronous Consensus Protocols

“…Read optimization for leader-based consensus is divided into two types: read lease [28,29] and read quorum [30,31]. However, the read lease method is not suitable for all the leaderless consensus protocols, including asynchronous consensus, because the leader process is generally required to serve as the leaseholder.…”