Energy consumption of ICT sector has sky-rocketed in recent years. Nowadays data centers are a major component of ICT sector. The number and size of the data centers has shown rapid growth. Internet giants like Google, IBM and Microsoft home large data center for cloud computing, internet applications, video and content sharing, and service hosting purposes. Data centers are also deployed by large organizations to home IT services. Various studies on energy consumption of data centers point out to the need of energy efficiency in such environments. Carbon footprint of ICT equipment is also a major concern as ICT devices emit large amount of CO2. The heat generated from these densely populated data centers needs large cooling units to keep their temperatures in operational range. These cooling units add to the total energy consumption and have their own carbon footprint.

Our contribution in this work is providing the motivation for the study of energy-efficiency in data center, highlighting the research issues, providing a data center simulation environment and a green data center resource scheduling approach, and providing a solution to the issue of high end-to-end delay regarding causal data in data centers.

Our contribution in the field of energy-efficiency in large-scale systems results in:
 Motivation for such study
 Research issues in the field of energy-efficiency in large-scale systems
 Simulation environment for energy-efficient data centers
 Data Center Energy-Efficient Resource Scheduling algorithm (DCEERS)
 Reducing the delay of causal data while ensuring energy-efficiency in data centers
 Studying the effects of DCEERS on network parameters.