Arun Kejariwal is a software engineer at Twitter, where he works on research and development of novel techniques for time series analysis. He open sourced R packages - AnomalyDetection and BreakoutDetection - which have been widely used in a variety of domains such as, but not limited to, medicine, social ecology, sports. Prior to joining Twitter, Arun worked on research and development of practical and statistically rigorous methodologies to deliver high performance, availability, and scalability in large-scale distributed clusters. Some of the techniques he helped develop have been published in peer-reviewed international conferences and journals. John Allspaw is currently Operations Engineering Manager at Flickr, the popular photo site. He has had extensive experience working with growing web sites since 1999. These include online news magazines Salon.com, InfoWorld.com, Macworld.com and social networking sites that experienced extreme growth (Friendster and Flickr). During his time at Friendster, traffic increased 5X. He was responsible for their transition from a couple dozen servers in a failing data center to over 400 machines across two data centers, and the complete redesign of the backing infrastructure. When he joined Flickr, they had 10 servers in a tiny data center in Vancouver; they are now located in multiple data centers across the US. Prior to his web experience, Allspaw worked in modeling and simulation as a mechanical engineer doing car crash simulations for the NHTSA.