Upgrade of the IaaS cloud: Issues and potential solutions in the context of high-availability

Cloud systems need to be upgraded to improve their performance, fix bugs, deploy new software versions, etc. Maintaining the availability of the services delivered by the system during upgrades is a big challenge, especially in the case of telecom systems where high-availability is a requirement. In this paper, we discuss some challenges and issues related to the upgrade of cloud systems in the context of high availability. We describe our initial ideas of a potential solution for systems providing infrastructure as a service (IaaS). As part of this solution, we define an infrastructure resource information model designed for the purpose of upgrade, the related upgrade actions, and the dependencies to be handled in the infrastructure layer. We also investigate existing cloud configuration management tools as candidates to use as upgrade engine.