Are quorums an alternative for data replication?

TLDR

Data replication is increasingly vital in parallel systems, yet maintaining consistency across replicas in cluster architectures causes severe scalability problems, prompting the suggestion of quorums to reduce replication overhead. The study aims to analyze various quorum types to understand their practical behavior and demonstrate that the conventional read‑one/write‑all‑available strategy is the best choice across multiple criteria. The authors evaluate several quorum types by analyzing their behavior in practice and comparing them against the read‑one/write‑all‑available approach across multiple selection criteria. The evaluation challenges assumptions about quorum‑based replication and shows that the read‑one/write‑all‑available strategy outperforms quorum approaches, offering simplicity and flexibility for cluster developers.

Abstract

Data replication is playing an increasingly important role in the design of parallel information systems. In particular, the widespread use of cluster architectures often requires to replicate data for performance and availability reasons. However, maintaining the consistency of the different replicas is known to cause severe scalability problems. To address this limitation, quorums are often suggested as a way to reduce the overall overhead of replication. In this article, we analyze several quorum types in order to better understand their behavior in practice. The results obtained challenge many of the assumptions behind quorum based replication. Our evaluation indicates that the conventional read-one/write-all-available approach is the best choice for a large range of applications requiring data replication. We believe this is an important result for anybody developing code for computing clusters as the read-one/write-all-available strategy is much simpler to implement and more flexible than quorum-based approaches. In this article, we show that, in addition, it is also the best choice using a number of other selection criteria.