Staged deployment in mirage, an integrated software upgrade testing and distribution system

Despite major advances in the engineering of maintainable and robust software over the years, upgrading software remains a primitive and error-prone activity. In this paper, we argue that several problems with upgrading software are caused by a poor integration between upgrade deployment, user-machine testing, and problem reporting. To support this argument, we present a characterization of softwareupgrades resulting from a survey we conducted of 50 system administrators. Motivated by the survey results, we present Mirage, a distributed framework for integrating upgrade deployment, user-machine testing, and problem reporting into the overall upgrade development process. Our evaluation focuses on the most novel aspect of Mirage, namely its staged upgrade deployment based on the clustering of usermachines according to their environments and configurations. Our results suggest that Mirage's staged deployment is effective for real upgrade problems.