About me

I am a postdoctoral researcher in the Computer Science Department at Carnegie Mellon University. I am advised by Professor Peter Steenkiste and I work with the XIA team on creating future Internet architectures.

My research interests span systems and networking. I am also interested in applying statistics, machine learning, and visualization techniques to solve systems/networking problems.

I completed my Ph.D. in the Electrical & Computer Engineering department at CMU in May 2013. I worked at the Parallel Data Lab (PDL) and was advised by Professor Greg Ganger. My research focused on problem diagnosis tools for cloud environments. In 2007, I appeared in a PhDComics strip encouraging CS grad students to wear lab coats to work. In my spare time, I enjoy playing tennis, running, and photography.

Dissertation research

My dissertation focused on a novel technique, called request-flow comparison, for automatically localizing the sources of performance degradations in distributed services, such as GFS or Bigtable. Such changes are common and are extremely difficult to diagnose manually because the problem could be contained in any one of the distributed system's many components or, worse, may be a result of interactions among them. My dissertation describes request-flow comparison and how we used an implementation of it, called Spectroscope, to diagnose real problems in distributed services, including select ones within Google. Request-flow comparison combines systems research, statistics, machine learning, and visualization to accomplish its goals.

Postdoctoral research

My postdoctoral research encompasses two related projects. The first focuses on enabling evolvability for inter-domain routing. BGP, the Internet's inter-domain routing protocol, is extremely important: it is responsible for connecting all of the machines on the Internet. But, it is outdated and riddled with critical flaws. BGP is also architecturally rigid, meaning that it cannot be easily evolved or changed. To help, we are working to identify the minimum set of modifications that must be made to BGP to allow it to facilitate quick Internet-wide deployment of critical fixes and replacement protocols. For the second project, I am working to create novel routing protocols that are better suited for today's sophisticated edge networks.

Selected publications

  • Bootstrapping evolvability for inter-domain routing. Raja R. Sambasivan, David Tran-Lam, Aditya Akella, Peter Steenkiste. HotNets'15.
    [Paper] [Slides]

  • Diagnosing performance changes by comparing request flows. Raja R. Sambasivan, Alice X. Zheng, Michael De Rosa, Elie Krevat, Spencer Whitman, Michael Stroucken, William Wang, Lianghong Xu, Gregory R. Ganger. NSDI'11.
    [Abstract] [Paper] [Slides] [Talk video] [Code]

  • So, you want to trace your distributed system? Key design insights from years of practical experience. Raja R. Sambasivan, Rodrigo Fonseca, Ilari Shafer, Gregory R. Ganger. CMU-PDL-14-102.
    [Abstract] [Paper]

  • Visualizing request-flow comparison to aid performance diagnosis in distributed systems. Raja R. Sambasivan, Ilari Shafer, Michelle L. Mazurek, Gregory R. Ganger. IEEE Transactions on Visualization and Computer Graphics (Proc. Information Visualization 2013), Vol. 19, no. 12, Dec. 2013.
    [Abstract] [Paper] [Slides] [Video figure] [Code]

  • Automated diagnosis without predictability is a recipe for failure. Raja R. Sambasivan and Gregory R. Ganger. HotCloud'12.
    [Abstract] [Paper] [Slides] [Talk video]

  • Ursa Minor: Versatile cluster-based storage. Michael Abd-El-Malek, William V. Courtright II, Chuck Cranor, Gregory R. Ganger, James Hendricks, Andrew J. Klosterman, Michael Mesnier, Manish Prasad, Brandon Salmon, Raja R. Sambasivan, Shafeeq Sinnamohideen, John D. Strunk, Eno Thereska, Matthew Wachs, Jay J. Wylie. FAST'05.
    [Abstract] [Paper]

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