A Framework for the Coordination of Multiple Autonomic Managers in Cloud Environments

One of the main reasons for the wide adoption of Cloud Computing is the flexibility in which resources and software services are provisioned on demand through the concept of elasticity. Implementing elasticity to tackle varying workloads while optimizing infrastructures (e.g. utilization rate) and fulfilling applications´ requirements on Quality of Service still remains an open issue and should be addressed by self-adaptation techniques able to manage complexity and dynamism. However, since Cloud systems are organized indifferent but dependent Cloud layers, self-management decisions taken in isolation in a certain layer may indirectly interfere with the decision taken by an other layer and globally affect the performance of the whole Cloud stack. Indeed, non-coordinated managers may lead to conflicting decisions and consequently to non-desired states. This paper proposes a framework for the coordination of multiple autonomic managers in Cloud systems. This framework introduces two kinds of managers: (i) one for each application, and (ii)another for the infrastructure. To tackle the problem of interferences between these Cloud autonomic managers, we propose a coordination protocol based on inter-manager events and actions along with synchronization mechanisms. The goal is to improve the synergy between layers in a loose-coupling manner. We evaluated the approach through an experimental scenario on Grid´5000, a real physical infrastructure testbed. In this use case, we show that our framework improves the synergy between cloud systems while dealing with conflicting objectives and negative interferences.