Enabling workflow repeatability with virtualization support.

The value of workflows to the scientific community spans over time and space. Not only results but also performance and resource consumption of a workflow need to be replayed over time and in varying environments. Achieving such repeatability in practice is challenging due to changes in software and infrastructure over time. In this work, we introduce a new abstraction that builds on the concept of virtual appliance to enable workflow repeatability. We have also developed a novel architecture to leverage this abstraction and realized it into a system implementation that supports a popular workflow management system and builds on a federated in-production environment. We demonstrate the effectiveness of our approach by examining various aspects of workflow repeatability. Our results show that workflows can be replayed with 2% fidelity when considering their walltime as performance metric.