© 2013, IJARCSSE All Rights Reserved Page | 379 Volume 3, Issue 9, September 2013 ISSN: 2277 128X International Journal of Advanced Research in Computer Science and Software Engineering Research Paper Available online at: www.ijarcsse.com Server Consolidation Algorithms for Cloud Computing Environment: A Review Susheel Thakur * Arvind Kalia Jawahar Thakur Student M.Tech, Computer Science, Professor, Associate Professor, Himachal Pradesh University, Shimla Himachal Pradesh University, Shimla Himachal Pradesh University, Shimla India India India Abstract — Virtualization technology provides the ability to transfer virtual machines (VM) between the physical systems using the technique of live migration mainly for improving the efficiency. Server consolidation through live migration is an efficient way towards energy conservation in cloud data centers. The main objective of this study is to prevent server sprawl, which refers to the usage of multiple-utilized servers in data centers incurring high system management cost. To prevent server sprawl, server consolidation aims at reducing the number of server machines used in the data centers by consolidating load and enhancing resource utilization of physical systems. Although a lot of research and study has been conducted on server consolidation, a range of issues involved have mostly been presented in isolation of each other. Therefore, here an attempt has been made to present a comprehensive survey to study the different server consolidation algorithms in a cloud computing environment. Keywords— Cloud computing, live migration, Load balancing, Server Sprawl, Virtual Machine Monitor (VMM). I. INTRODUCTION With the rapid development in the processing, storage technologies and the success of the internet, computing resources have become reasonable, powerful and globally available than ever before. Personnel in businesses are trying to find out methods to cut costs while maintaining the same performance standards. Their aspirations to grow have led them to try new ideas and methods even under the peer pressure of limiting computing resources. This realization has enabled the actualization of a new model for computing called cloud computing, in which the resources (e.g. cpu, network, etc.) are provided through the internet to user as general utilities in a pay-as-you-go and on-demand basis. Cloud Computing is defined by NIST[10] as a model for enabling convenient, on demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction. For simplicity, a cloud is a pool of physical computing resources i.e. a set of hardware, processors, memory, storage, networks, etc which can be provisioned on demand into services that can grow or shrink in real-time scenario[16]. Virtualization plays a vital role for managing and coordinating the access from the resource pool. A virtualized environment that enables the configuration of systems (i.e. compute power, bandwidth and storage) as well as the creation of individual virtual machines is the key features of the cloud computing. Virtualization is ideal for delivering cloud services. Virtualization Technology enables the decoupling of the application payload from the underlying physical hardware and provides virtualized resources for higher-level applications. An important feature of a virtual machine is that software running inside it is limited to resources and abstractions provided by the virtual machine (VM). The software layer that provides the virtualization is called virtual machine monitor (VMM). VMM virtualizes all of the resources of physical machine, thereby supporting the execution of multiple virtual machines. Virtualization can provide remarkable benefits in cloud computing by enabling VM migration to balance load across the data centers [7]. In the surge of rapid usage of virtualization, migration procedure has been enhanced due to the advantages of live migration say server consolidation and resource isolation. Live migration of virtual machines [4, 9] is a technique in which the virtual machine seems to be active and give responses to end users all time during migration process. Live migration facilitates energy efficiency, online maintenance and load balancing [8]. Live migration helps to optimize the efficient utilization of available cpu resources. Server consolidation is an approach for the efficient usage of computer server resources in order to reduce the total number of servers or server locations that an organization requires. This approach was developed in response to the problem of “server sprawl”. Server sprawl is a situation in which multiple underutilized servers occupies more space and consume more resources that can be justified by their workload. Many organizations are moving towards server consolidation to reduce infrastructure complexity, improve system availability and save money. With increasingly powerful computing hardware, including multi-core servers; organizations can run large workloads and more applications on few servers. Reducing the numbers of servers has tangible benefits for the data center as well. Server Consolidation can be categorized into: 1. Location Consolidation-The number of physical locations containing hardware is reduced.