I- Introduction

II- DCN problems leading to energy and cost inefficiency

III- Steps to green data center networks

IV- Summary and Discussion

V- Conclusion

References

Abstract

Data Center Networks (DCNs) are attracting immense interest from the industry, research and academia to keep pace with the increase of Internet services demands. One of the major concerns that draws the attention of researchers is the exponential growth of the energy consumption and carbon emission of the DCNs. Studies conducted to identify the causes of the increasing energy consumption have proved that the growing size of computing demand, the over-provisioning of the networking resources, the under-utilization of the infrastructure, the fault-tolerance, the high bandwidth exigence and the inefficient hardware and cooling structure are leading to considerable energy waste. Therefore, in recent years, new data center (DC) architectures are proposed where new hardware types and new technologies are implemented for the sake of energy efficiency. Other efforts are focusing on designing algorithms and strategies to enhance the utilization of the network resources. Replacing brown power by renewable energy was also one of the attractive ideas to minimize the energy costs. In this survey paper, we will present energy-related problems in data centers and review the state of the art of the research literature on energy efficient architectures, techniques, technologies, resource management, and thermal control and monitoring. Additionally, we present the challenges facing each approach and the strategies to build a green DC. This paper serves as a specification document that shows step by step how to minimize the energy consumption of different components of the system.

INTRODUCTION

In the few recent years, data center networks have witnessed an unprecedented growth [1]. This growing importance of data centers is caused by the emergence of IT operations worldwide that replaced the traditional business models. To keep pace with the unceasing demand in services, considerable research efforts are conducted to design a performant interconnection network with a cost-effective deployment and maintenance. Generally, the design goals of data center networks are: high scalability, simple installation, small number of wires, an efficient routing algorithm that must be itself scalable, low latency, high bandwidth, sufficient runtime performance by installing the highest performance equipment to be always ready for peak traffic times, and good thermal control by managing the cooling infrastructure and avoiding any over-heating problems. In addition, with data availability at stake, the robustness of the data center network becomes more critical than ever. Hence, storage machines and network devices are duplicated to protect the loss of clients data. Based on these critical requirements, many efforts are trying to build high performance data centers that include all the QoS (Quality of Service) needs including PTNet [2] and LaCoDa [3]. However, implementing a huge number of devices for the sake of scalability, adding redundant machines to face failures, installing high capacity equipment to provide a 24/7 availability and investing in a power hungry cooling infrastructure contribute to make the data center networks one of the largest consumers of energy in the world. In fact, statistics in [4] predict that the world power consumption of data centers will rise from 1.1%-1.5% in 2011 to 8% in 2020 due to over-provisioning. This growth of electrical power consumption arouses many concerns to investigate the impact on the environment. Studies found that the IT sector contributes approximately in 2% of the total green-house gas emissions where 37% of this gas is caused by networking equipment [5]. Motivated by this high energy consumption and effects on the environment, many researchers, during the past years, have focused on the design of green data center networks. However, even if significant progress has been made, there is still a large opportunity to save energy since existing approaches generally handle a specific source of power waste and do not take a holistic approach to minimize the energy consumption of all parts of a DC infrastructure.