This paper introduces dual-quorum replication, a novel data replication algorithm designed to support Internet edge services. Dual-quorum replication combines volume leases and quorum based techniques in order to achieve excellent availability, response time, and consistency for read/write objects when the references to each object (a) tend not to exhibit high concurrency across multiple nodes and (b) tend to exhibit bursts of read-dominated or write-dominated behavior. Through both analytical and experimental evaluation of a prototype, we show that the dual-quorum protocol can (for the workloads of interest) approach the excellent performance and availability of Read-One/Write-All-Asynchronously (ROWA-A) epidemic algorithms without suffering the weak consistency guarantees and resulting design complexity inherent in ROWA-A systems.
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