Evaluation of Cloud-RAID: A Secure and Reliable Storage above the Clouds

Cloud Computing as a service-on-demand architecture has grown in importance over the previous few years. One driver of its growth is the ever increasing amount of data which is supposed to outpace the growth of storage capacity. The usage of cloud technology enables organizations to manage their data with low operational expenses. However, the benefits of cloud computing come along with challenges and open issues such as security, reliability and the risk to become dependent on a provider for its service. In general, a switch of a storage provider is associated with high costs of adapting new APIs and additional charges for inbound and outbound bandwidth and requests. In this paper, we present a system that improves availability, confidentiality and reliability of data stored in the cloud. To achieve this objective, we encrypt user´s data and make use of the RAID-technology principle to manage data distribution across cloud storage providers. We conduct a proof-of-concept testbed experiment for our application to evaluate the performance and cost effectiveness of our approach. We deployed our application using eight commercial cloud storage repositories in different countries. Our approach allows users to avoid vendor lock-in, and reduces significantly the cost of switching providers. We also observed that our implementation improved the perceived availability and, in most cases, the overall performance when compared with individual cloud providers. Moreover, we estimated the monetary costs to be competitive to the cost of using a single cloud provider.