Comparing Provisioning and Scheduling Strategies for Workflows on Clouds

Cloud computing is emerging as a leading solution for deploying on-demand applications in both the industry and the scientific community. An important problem which needs to be considered is that of scheduling tasks on existing resources. Since clouds are linked to grid systems much of the work done on the latter can be ported with some modifications due to specific aspects that concern clouds, e.g., virtualization, scalability and on-demand provisioning. Two types of applications are usually considered for cloud migration: bag-of-tasks and workflows. This paper deals with the second case and investigates the impact virtual machine provisioning policies have on the scheduling strategy when various workflow types and execution times are used. Five provisioning methods are proposed and tested on well known workflow scheduling algorithms such as CPA, Gain and HEFT. We show that some correlation between the application characteristics and provisioning method exists. This result paves the way for adaptive scheduling in which based on the workflow properties a specific provisioning can be applied in order to optimize execution times or costs.