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Sustainable energy sources such as renewable energies are replacing dirty sources of energy in order to address the environmental challenges of the century. In order to operate data centres with renewable energies we have to mitigate their volatile and variable nature. In this paper, we present the Energy Adaptive Software Controller (EASC), a generic software controller and interface that developers can use to make their application adaptive to renewable energy availability. Adaptivity is realized through the concept of working modes which allow to run an application under various performance levels. We advocate for a collaborative approach involving the developers of the applications in order to use the renewable energies more efficiently. The notion of EASC allows to abstract away the details of application scheduling, execution, and monitoring. We demonstrate the applicability and genericity of the EASC concept through four different instantiations. These instantiations cover two types of applications: task-oriented and service-oriented, and two kind of computing environments: Infrastructure-as-a-Service, and Platform-as-a-Service. The EASC has been trialled in the data centre of the healthcare agency of Trento, Italy and in the laboratory of HP Milan, Italy, with a mix of energy sources: national grid and local solar panels. The experimental results show how the EASC allowed to increase the renewable energies usage of 14% and 4.73% for Trento and HP Labs trials, respectively. |
