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Dr. Murat Demirbas

University at Buffalo

Friday, May 3, 2019
11:00AM – 12:00PM – HEC 113


Many distributed databases employ consensus protocols to ensure that data is replicated in a strongly-consistent manner on multiple machines despite failures and concurrency. Unfortunately, these protocols show widely varying performance under different network, workload, and deployment conditions, and no previous study offers a comprehensive dissection and comparison of their performance.  To fill this gap, we study single-leader, multi-leader, hierarchical multi-leader, and leaderless (opportunistic leader) Paxos-based protocols, and present a comprehensive evaluation of their performance in local area networks (LANs) and wide area networks (WANs). We present an analytic modeling of the protocols using queuing theory and show simulations under varying controlled parameters. To cross-validate the analytic model, we also present empirical results from our prototyping and evaluation framework, Paxi.
We distill our findings to simple throughput and latency formulas over the most significant parameters. These formulas enable the developers to decide which category of protocols would be most suitable under given deployment conditions.


Murat Demirbas is a Professor of Computer Science & Engineering at University at Buffalo, SUNY. Murat received his Ph.D. from The Ohio State University in 2004 and did a postdoc at the Theory of Distributed Systems Group at MIT in 2005. His research interests are in distributed and networked systems and cloud computing. Murat received an NSF CAREER award in 2008, UB Exceptional Scholars Young Investigator Award in 2010, UB School of Engineering and Applied Sciences Senior Researcher of the Year Award in 2016. He maintains a popular blog on distributed systems at