Cloud computing is emerging trend of IT delivery in which application data and IT resources are rapidly and elastically provisioned and provided as standardized subscription to users over the internet in a flexible pricing model and effort by interacting with the service provider. . Security of cloud computing is a major factor in the cloud computing platform, as users often store sensitive information and critical application with cloud service providers but these providers may be not trusted. Moreover, the interoperability among the endowment and the flexibility of services from one provider to another is very crucial for the customer to maximize the expected from the cloud. Dealing with the solo cloud providers is predicted to become less popular with customers due to risks of service availability failure , the possibility of malicious user can penetrate the cloud by impersonating a legitimate user, there by infecting the entire cloud thus affecting many user and user gets stick on to the single cloud(vendor lock-in) and has to get all the services from this infected single cloud. A shift towards multi-clouds assists the user to utilize services from multiple cloud service providers in case of failure from single cloud. The efficient dynamic collaboration of multiple clouds provide several potential benefits, such as high availability, scalability, fault tolerance and reduced infrastructural cost.

1. S. Ortiz Jr. , "The Problem with Cloud Computing Standardization," Computer, July 2011, pp. 13-16.
2. M. P. Papazoglou and W. van den Heuvel, "Blueprinting the Cloud," IEEE Internet Computing, Nov. /Dec 2011, pp. 74-79
3. B. Rochwerger et al. , "Reservoir—When One Cloud Is Not Enough," Computer, Mar. 2011, pp. 44-51.
4. Shaik. AafreenNaaz, Pothireddygari. Ramya, P. Vishunu Vardhan Reddy. , "Cloud Computing: Use of Multi-Clouds" pp. 295-304
5. R. Thandeeswaran, S. Subhashini, N. Jeyanthi1, M. A. Saleem Durai, "Secured Multi- Cloud Virtual Infrastructure with Improved Performance", cybernetics and information technologies XII, (2), pp. 11-22, 2012
6. Mukesh Singhal and Santosh Chandrasekhar, Tingjian Ge, Ravi Sandhu and Ram Krishnan, Gail-Joon Ahn, and Elisa Bertino "Collaboration in Multicloud Computing Environments: Framework and Security Issues", Published by the IEEE Computer Society IEEE, 2013

Multi-cloud proxy Cost Effective Security Cloud Service Provider High Availability