International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 03 Issue: 04 | April-2016 www.irjet.net p-ISSN: 2395-0072 © 2016, IRJET ISO 9001:2008 Certified Journal Page 2734 A Review on Different Existing Load Balancing Approaches for Cloud Saurabh Jain 1 , Dr. Varsha Sharma 2 1 Student, School of Information Technology, RGPV, Bhopal, MP, India 2 Assistant Professor, School of Information Technology, RGPV, Bhopal, MP, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Cloud computing is one of the emerging technologies in modern IT era. It provides on demand IT related resources to the client on the rent basis. The key concept behind cloud computing is Dzvirtualizationdz. Virtualization is an interface which separate hardware from software and provides the benefits of server consolidation and live migration. A main benefit of virtualization is that, it allows creating multiple virtual machines (VMs) on a single physical machine (PM). Since multiple users share the cloud resources, so there may be situation when the PM is overloaded or under loaded. VM migration is a unique solution to mitigate both situations. Performance of the PM degrades when the PM is overloaded or under loaded. If load balancing in cloud is not handled properly, then it will increase the energy consumption and minimize the provider profit. Hence, load balancing in cloud is the prime requirement of the cloud provider. Load balancing in cloud is a challenging task due to change in user requirement at the run time. When the PM is overloaded or underloaded, some VMs need to be migrated. VM migration consists of three steps: source PM selection, VM selection and the last step target PM selection. Numerous load balancing algorithms have been proposed in the literature. This paper discussed various existing load balancing approaches with their comparisons. Key Words: Virtualization, migration, energy efficient, virtual machine, physical machine 1. INTRODUCTION Cloud computing is one of the fascinating technology in the field of computer science. It became so popular due to its attractive features like on-demand services, utility based model, ease of use etc. According to Gartner’s report [ͳ], the Core technology behind the cloud computing is the virtualization [2, 3]. Virtualization is the abstraction layer between the hardware and software. It divides the physical resources into the multiple types and allows the sharing of physical resources. Virtualization increases the resource utilization because multiple users share the same physical resources but, it also introduces the need of load balancing. If the load is distributed properly then it will increase the resource utilization and reduce the energy consumption. During the study of load balancing approaches it is found that if the load is distributed effectively then it will minimize the energy consumption and total simulation time. Load balancing approach can be static or dynamic. Static approach is more appropriate for the cloud. The one where information about system is not important and working is less complex comes under static scheme whereas in the dynamic approach load balancing decision is taken based on the previous system information. Most of the existing load balancing [4-6] approaches use thresholds to represent the overloaded and underutilized situation where lower threshold represents the under loaded situation and upper threshold is use to define the overloaded situation. To handle the overloaded and under loaded situations VM migration is used which move the VM from one PM to another PM. VM migration is the important feature of virtualization and is used to deal with the overloaded, under loaded and hot spot situations. Hence, VM migration allows the flexibility to resource provisioning. Several load balancing approaches have been proposed in the last few years. This paper gives the overview of some approaches with their anomalies. 2. Following are the Goals of load balancing in Cloud computing 1) To improve the performance of the cloud services. 2) To have a backup plan in case the system fails even partially. 3) Increase the availability of the resources. 4) To maintain the system stability. 5) To minimize the number of SLA violations. 3. Challenging Issue in load balancing Main challenging issues for the load balancing are [3] 1) The load balancing approach imposed some overhead to process the request because it needs some resources for the processing. So this overhead should be minimize as possible 2) Since load in the cloud change dynamically, so it is very difficult to design an efficient load balancing approach for the cloud environment. 3) To balance the system, scheduler migrates the VM which reduce the system performance. So a load balancing approach must reduce the number of migrations.