Scheduling Scientific Workflows Elastically for Cloud Computing

Most existing workflow scheduling algorithms only consider a computing environment in which the number of compute resources is bounded. Compute resources in such an environment usually cannot be provisioned or released on demand of the size of a workflow, and these resources are not released to the environment until an execution of the workflow completes. To address the problem, we firstly formalize a model of a Cloud environment and a workflow graph representation for such an environment. Then, we propose the SHEFT workflow scheduling algorithm to schedule a workflow elastically on a Cloud computing environment. Our preliminary experiments show that SHEFT not only outperforms several representative workflow scheduling algorithms in optimizing workflow execution time, but also enables resources to scale elastically at runtime.