Overhead Analysis as One Factor Scalibility of Private Cloud Computing for IAAS Service Teguh Bharata Adji, Faisal Suryadi Nggilu, Sujoko Sumaryono Abstract— The rapid development of technology leads to improvement in a variety of computing concepts, information and communication technology(ICT). The ICT environment is become more complex and costly. Cloud Computing is one of phenomenon int the new ICT services, Cloud Computing model has three categories of services : Infrastructure As A Service (IAAS), Platform As A Service (PAAS), Software As A Service (SAAS). It also has four deployment models which are private cloud computing, community cloud, public cloud and hybrid Cloud. This research aims to determine the overhead of the virtualization environment. It is expected the private cloud with virtual technology, that utilizes the maximum resources does not degrade server scalability. The implementation of private cloud is using OpenStack with configuration multiple interfaces multiple servers. The results of the thesis indicate that the overhead of a single virtual machine is 114 ms (database server) and 212 ms (web server), to ten virtual machines are active 615 ms (database server) and 786 ms (web server). Overhead that occurs on a single VM can still be neglected, despite the performance degradation with increasing number of active virtual machines the execution time of servers application tends to be linear close to shape belongs to the physical servers. Index Terms— Overhead, private cloud computing, IAAS, OpenStack, multiple interfaces multiple servers. ——————————  —————————— 1 INTRODUCTION S the rapid development of technology leads to im- provement in a variety of computing concepts, the in- formation and communication technology (ICT) envi- ronment becomes more complex and costly. Provision of reli- able infrastructure have consequences for the ICT users to be able to use it effectively and efficiently. Cloud computing is one of development phenomenon in the new ICT services. Cloud Computing is a model which provides computing resources or information technology (e.g., software, processing power, storage.) that allows customers to "take and use" resources on-demand, via the internet (NIST, 2011). With the cloud computing, it will change the paradigm of the company or organization in ICT investment. Cloud com- puting can be promoted to consolidate ICT infrastructure, simplify management, maximizing the utilization of compu- ting resources and at the end it would be able to save the op- erational costs. Infrastructure As a Service (IAAS) is a service that "rent" the basic technology information resources, which includes media storage, processing power, memory, operating system, network capacity, etc. which can be used by users to run ap- plications virtually. The implementation of virtual technology that utilizes the maximum resources of server, is expected to reduce its scala- bility to the virtualization environment such as overhead. 2 LITERATURE REVIEW Cloud computing is one of development phenomenon in the new ICT services. Cloud Computing is a model which pro- vides computing resources (e.g., software, processing power, storage.) that allows customers to "take and use" resources on- demand via the internet (NIST, 2011). There are four proposed ontology which is expected to be a framework and guidance in conducting research in cloud computing. This ontology consist of cloud application (software as a service), cloud software environment (platform as a service), cloud software infrastruc- ture ( infrastructure as a service, data as a service, communica- tion as a service ), software kernel, firmware / hardware ( hardware as a service) (Youseff, 2008). Infrastructure As a Service (IAAS) is a service that "rent" the basic information technology resources, which include media storage, processing power, memory, operating system, net- work capacity, etc. which can be used by users to run applica- tions virtually. In a virtualized environment, ( Nurhaida, 2009) performed overhead measurement, linearity, performance isolation and the use of hardware resources in a virtualized environment. The research used VMWare ESX 3.5.0 as virtual- ization application. 2.1 Virtual Server scalibility Scalability is the ability to improve system performance grad- ually in accordance with the work load by increasing the number of resources. To evaluate overhead due to the virtual- ization mechanisms, we compare the execution time of an ap- plication running on a non-virtualized operating system (Ta) with another execution time of the same application run with- in a single virtual machine (Tav). The overhead may be negli- gible for a virtual machine and becomes significant when sev- eral virtual machines running at the same time (context switch overhead may exist even if no application is executed on the other virtual machines) and the formula is : Ov = Tav – Ta ….......................... ( 2.1) Meanwhile, Ta is also compared with Tanv when some virtual machines n running at the same time. In this scenario, only a virtual machine actually runs the application. The other n − 1 VMs are not running any application. A International Journal of Scientific & Engineering Research, Volume 4, Issue 5, May-2013 ISSN 2229-5518 171 IJSER © 2013 http://www.ijser.org IJSER