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The Taub Faculty of Computer Science Events and Talks

ceClub: Unveiling the Secrets of High-Performance Datacenters
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Michael Schapira (Hebrew University of Jerusalem)
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Wednesday, 17.06.2015, 11:30
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EE Meyer Building 861
Many architectures for high-performance datacenters have been proposed to meet the ever-growing traffic demands. Surprisingly, recent studies show that even random datacenter topologies outperform much more sophisticated designs, achieving near-optimal throughput and bisection bandwidth, high resiliency to failures, incremental expandability, high cost efficiency, and more. While this highlights the suboptimality of existing datacenters, the inherent unstructuredness and unpredictability of random datacenter topologies pose obstacles to their adoption in practice. Can these guarantees be achieved by well-structured, deterministic datacenter architectures? We provide a surprising affirmative answer to this question. We show, through a combination of theoretical analyses, extensive simulations, and experiments with e network emulator, that any network topology that belongs to the extensively studied class of “expander graphs” (as indeed do random graphs) comes with these benefits, and more, thus opening a new avenue for highperformance datacenter design: turning ideas from the rich literature on deterministically constructing expander graphs into an operational reality. We leverage these insights to propose Xpander, a novel deterministic datacenter architecture that achieves all of the above desiderata, and significantly outperforms traditional datacenter designs. We discuss challenges en route to deploying Xpander (e.g., cabling, routing) and explain how these can be resolved. Our results suggest that the key to future progress on designing high-performance datacenters lies in exploring design tradeoffs within the space of expander datacenters.

Joint work with Michael Dinitz (Johns Hopkins University) and Asaf Valadarsky (Hebrew University of Jerusalem)

Michael Schapira ( is a senior lecturer at the School of Computer Science and Engineering, the Hebrew University of Jerusalem. His research interests lie in the design and analysis of protocols and architectures for (Inter)networked environments (e.g., routing, congestion control, traffic engineering, and more). Prior to joining the Hebrew University he was a visiting scientist at Google NYC and a postdoctoral researcher at UC Berkeley, Yale University, and Princeton University. He is a recipient of the Allon Fellowship (2011), a Microsoft Research Faculty Fellowship (2013), the IETF/IRTF Applied Networking Research Prize (2014), the Hebrew University President’s Prize (2014), and the Krill Prize (2015). He holds a BSc in Math and Computer Science, a BA in Humanities, and a PhD in Computer Science from the Hebrew University of Jerusalem.