Improving Cloud Service Resilience using Brownout-Aware Load-Balancing
2014 (English)Conference paper (Refereed)
We focus on improving resilience of cloud services (e.g., e-commerce website), when correlated or cascading failures lead to computing capacity shortage. We study how to extend the classical cloud service architecture composed of a load-balancer and replicas with a recently proposed self-adaptive paradigm called brownout. Such services are able to reduce their capacity requirements by degrading user experience (e.g., disabling recommendations).
Combining resilience with the brownout paradigm is to date an open practical problem. The issue is to ensure that replica self-adaptivity would not confuse the load-balancing algorithm, overloading replicas that are already struggling with capacity shortage. For example, load-balancing strategies based on response times are not able to decide which replicas should be selected, since the response times are already controlled by the brownout paradigm.
In this paper we propose two novel brownout-aware load-balancing algorithms. To test their practical applicability, we extended the popular lighttpd web server and load-balancer, thus obtaining a production-ready implementation. Experimental evaluation shows that the approach enables cloud services to remain responsive despite cascading failures. Moreover, when compared to Shortest Queue First (SQF), believed to be near-optimal in the non-adaptive case, our algorithms improve user experience by 5%, with high statistical significance, while preserving response time predictability.
Place, publisher, year, edition, pages
IEEE Computer Society, 2014.
cloud, load-balancing, self-adaptation, control theory, statistical evaluation
Computer Systems Control Engineering
Research subject Computer Science
IdentifiersURN: urn:nbn:se:umu:diva-91327OAI: oai:DiVA.org:umu-91327DiVA: diva2:735567
33rd IEEE Symposium on Reliable Distributed Systems (SRDS 2014)
FunderSwedish Research CouncileLLIIT - The Linköping‐Lund Initiative on IT and Mobile CommunicationsLinnaeus research environment CADICS