Gurudatt Kulkarni, Ramesh Sutar, Jayant Gambhir / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 1,Jan-Feb 2012, pp.945-950 945 | P a g e “Cloud Computing-Storage as Service” Gurudatt Kulkarni 1 , Ramesh Sutar 2 , Jayant Gambhir 3 1, 2, 3 Lecturer in Marathwada Mitra Mandal’s Polytechnic, Thergoan, Pune Abstract-Storage as a Service is a business model in which a large company rents space in their storage infrastructure to a smaller company or individual.In the enterprise, SaaS vendors are targeting secondary storage applications by promoting SaaS as a convenient way to manage backups. The key advantage to SaaS in the enterprise is in cost savings -- in personnel, in hardware and in physical storage space. For instance, instead of maintaining a large tape library and arranging to vault (store) tapes offsite, a network administrator that used SaaS for backups could specify what data on the network should be backed up and how often it should be backed up. His company would sign a service level agreement (SLA) whereby the SaaS provider agreed to rent storage space on a cost-per- gigabyte-stored and cost-per-data-transfer basis and the company's data would be automatically transferred at the specified time over the storage provider's proprietary wide area network (WAN) or the Internet. If the company's data ever became corrupt or got lost, the network administrator could contact the SaaS provider and request a copy of the data. It covers the key technologies in Cloud Computing and Cloud Storage, several different types of clouds services, and describes the advantages and challenges of Cloud Storage after the introduction of the Cloud Storage reference model. Keywords-Storage, Public Cloud, S3, SLA 1.0 Introduction Storage as a Service is generally seen as a good alternative for a small or mid-sized business that lacks the capital budget and/or technical personnel to implement and maintain their own storage infrastructure. SaaS is also being promoted as a way for all businesses to mitigate risks in disaster recovery, provide long-term retention for records and enhance both business continuity and availability.Cloud storage is a service model in which data is maintained, managed and backed up remotely and made available to users over a network (typically the Internet). There are three main cloud storage models:[2]  Public cloud storage services, such as Amazon's Simple Storage Service (S3), provide a multi- tenant storage environment that’s most suitable for unstructured data.  Private cloud storage services provide a dedicated environment protected behind an organization’s firewall. Private clouds are appropriate for users who need customization and more control over their data.  Hybrid cloud storage is a combination of the other two models that includes at least one private cloud and one public cloud infrastructure. An organization might, for example, store actively used and structured data in a private cloud and unstructured and archival data in a public cloud. Figure1.0:- Cloud Computing Steps Cloud computing is about moving services, computation or data—for cost and business advantage— off-site to an internal or external, location-transparent, centralized facility or contractor. By making data available in the cloud, it can be more easily and ubiquitously accessed, often at much lower cost, increasing its value by enabling opportunities for enhanced collaboration, integration, and analysis on a shared common platform. Depending on the type of provided capability, there are four scenarios where Clouds are used as showed in Fig.1.1