Availability knob: Flexible user-defined availability in the cloud

Mohammad Shahrad, David Wentzlaff

Research output: Chapter in Book/Report/Conference proceedingConference contribution

17 Scopus citations


Failure is inevitable in cloud environments. Finding the root cause of a failure can be very complex or at times nearly impossible. Different cloud customers have varying availability demands as well as a diverse willingness to pay for availability. In contrast to existing solutions that try to provide higher and higher availability in the cloud, we propose the Availability Knob (AK). AK provides flexible, user-defined, availability in IaaS clouds, allowing the IaaS cloud customer to express their desire for availability to the cloud provider. Complementary to existing high-reliability solutions and not requiring hardware changes, AK enables more efficient markets. This leads to reduced provider costs, increased provider profit, and improved user satisfaction when compared to an IaaS cloud with no ability to convey availability needs. We leverage game theory to derive incentive compatible pricing, which not only enables AK to function with no knowledge of the root cause of failure but also function under adversarial situations where users deliberately cause downtime. We develop a high-level stochastic simulator to test AK in large-scale IaaS clouds over long time periods. We also prototype AK in OpenStack to explore availability-API tradeoffs and to provide a grounded, real-world, implementation. Our results show that deploying AK leads to more than 10% cost reduction for providers and improves user satisfaction. It also enables providers to set variable profit margins based on the risk of not meeting availability guarantees and the disparity in availability supply/demand. Variable profit margins enable cloud providers to improve their profit by as much as 20%.

Original languageEnglish (US)
Title of host publicationProceedings of the 7th ACM Symposium on Cloud Computing, SoCC 2016
EditorsYanlei Diao, Marcos K. Aguilera, Brian Cooper, Yanlei Diao
PublisherAssociation for Computing Machinery, Inc
Number of pages15
ISBN (Electronic)9781450345255
StatePublished - Oct 5 2016
Event7th ACM Symposium on Cloud Computing, SoCC 2016 - Santa Clara, United States
Duration: Oct 5 2016Oct 7 2016

Publication series

NameProceedings of the 7th ACM Symposium on Cloud Computing, SoCC 2016


Other7th ACM Symposium on Cloud Computing, SoCC 2016
Country/TerritoryUnited States
CitySanta Clara

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Computational Theory and Mathematics


  • Cloud availability
  • Cloud economics
  • Failureaware scheduling
  • Flexible availability
  • SLA


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