@conference {18546, title = {Answering what-if deployment and configuration questions with wise}, booktitle = {Proceedings of the ACM SIGCOMM 2008 conference on Data communication}, series = {SIGCOMM {\textquoteright}08}, year = {2008}, month = {2008///}, pages = {99 - 110}, publisher = {ACM}, organization = {ACM}, address = {New York, NY, USA}, abstract = {Designers of content distribution networks often need to determine how changes to infrastructure deployment and configuration affect service response times when they deploy a new data center, change ISP peering, or change the mapping of clients to servers. Today, the designers use coarse, back-of-the-envelope calculations, or costly field deployments; they need better ways to evaluate the effects of such hypothetical "what-if" questions before the actual deployments. This paper presents What-If Scenario Evaluator (WISE), a tool that predicts the effects of possible configuration and deployment changes in content distribution networks. WISE makes three contributions: (1) an algorithm that uses traces from existing deployments to learn causality among factors that affect service response-time distributions; (2) an algorithm that uses the learned causal structure to estimate a dataset that is representative of the hypothetical scenario that a designer may wish to evaluate, and uses these datasets to predict future response-time distributions; (3) a scenario specification language that allows a network designer to easily express hypothetical deployment scenarios without being cognizant of the dependencies between variables that affect service response times. Our evaluation, both in a controlled setting and in a real-world field deployment at a large, global CDN, shows that WISE can quickly and accurately predict service response-time distributions for many practical What-If scenarios.}, keywords = {content distribution networks, performance modeling, what-if scenario evaluation}, isbn = {978-1-60558-175-0}, doi = {10.1145/1402958.1402971}, url = {http://doi.acm.org/10.1145/1402958.1402971}, author = {Tariq,Mukarram and Zeitoun,Amgad and Valancius,Vytautas and Feamster, Nick and Ammar,Mostafa} }