Bootstrapping evolvability for inter-domain routing

Workshop papers
Raja R. Sambasivan, David Tran-Lam, Aditya Akella, Peter Steenkiste
In Proceedings of HotNets 2015
Publication year: 2015

It is extremely difficult to deploy new inter-domain routing protocols in today’s Internet.  As a result, the Internet’s baseline protocol for connectivity, BGP, has remained largely unchanged, despite known significant flaws.  The difficulty of deploying new protocols has also depressed opportunities for (currently commoditized) transit providers to provide value-added routing services.  To help, we identify the key deployment models under which new protocols are introduced and the requirements each poses for enabling their usage goals.  Based on these requirements, we argue for two modifications to BGP that will greatly improve support for new routing protocols.

Specialized storage for big numeric time series

Workshop papers
Ilari Shafer, Raja R. Sambasivan, Gregory R. Ganger
In Proceedngs of HotCloud 2013
Publication year: 2013

Numeric time series data has unique storage require- ments and access patterns that can benefit from special- ized support, given its importance in Big Data analyses. Popular frameworks and databases focus on addressing other needs, making them a suboptimal fit. This paper describes the support needed for numeric time series, suggests an architecture for efficient time series storage, and illustrates its potential for satisfying key require- ments.

Automated diagnosis without predictability is a recipe for failure

Workshop papers
Raja R. Sambasivan, Gregory R. Ganger
In Proceedings of HotCloud'12
Publication year: 2012

Automated management is critical to the success of cloud computing, given its scale and complexity. But, most systems do not satisfy one of the key properties required for automation: predictability, which in turn relies upon low variance. Most automation tools are not effective when variance is consistently high. Using automated performance diagnosis as a concrete example, this position paper argues that for automation to become a reality, system builders must treat variance as an important metric and make conscious decisions about where to reduce it. To help with this task, we describe a framework for reasoning about sources of variance in distributed systems and describe an example tool for helping identify them.

Categorizing and differencing system behaviors

Workshop papers
Raja R. Sambasivan, Alice X. Zheng, Eno Thereska, Gregory R. Ganger
In Proceedings of HotAC 2007
Publication year: 2007

Making request flow tracing an integral part of soft- ware systems creates the potential to better understand their operation. The resulting traces can be converted to per- request graphs of the work performed by a service, repre- senting the flow and timing of each request’s processing. Collectively, these graphs contain detailed and comprehen- sive data about the system’s behavior and the workload that induced it, leaving the challenge of extracting insights. Categorizing and differencing such graphs should greatly improve our ability to understand the runtime behavior of complex distributed services and diagnose problems. Clus- tering the set of graphs can identify common request pro- cessing paths and expose outliers. Moreover, clustering two sets of graphs can expose differences between the two; for example, a programmer could diagnose a problem that arises by comparing current request processing with that of an earlier non-problem period and focusing on the aspects that change. Such categorizing and differencing of system behavior can be a big step in the direction of automated problem diagnosis.