Abstract: “the development of worldwide networks, open systems and new technology trends a new type of computing where computational power is provided similar to utilities like water, gas or electricity. Cloud computing refers to the concept of grid computing, utility computing and virtualization. It elevates knowledge management to newer heights by providing huge data storage and computational power with feature of elasticity and scalability. It has a lot of advantages but still this field in its infancy as far as implementation and usage are concerned. The lack of security in cloud represents an obstacle for most enterprises for moving into the cloud. The purpose of this paper is to address the challenges and threats in deployment models and discuss obstacles in implementation of cloud computing. So researcher need to work at this high developing paradigm’s highlighted areas.”

Keywords: Datacenters, Data Privacy, Hypervisor, Security, Utility Computing and Virtualization.