  Major cloud providers such as Microsoft, Google, Facebook and Amazon rely
heavily on datacenters to support the ever-increasing demand for their
computational and application services. However, the financial and carbon
footprint related costs of running such large infrastructure negatively impacts
the sustainability of cloud services. Most of existing efforts primarily focus
on minimizing the energy consumption of servers. In this paper, we devise a
conceptual model and practical design guidelines for holistic management of all
resources (including servers, networks, storage, cooling systems) to improve
the energy efficiency and reduce carbon footprints in Cloud Data Centers
(CDCs). Furthermore, we discuss the intertwined relationship between energy and
reliability for sustainable cloud computing, where we highlight the associated
research issues. Finally, we propose a set of future research directions in the
field and setup grounds for further practical developments.
