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Cloud computing refers to using a third-party network of remote servers hosted on the internet to store and manage all your data, rather than local server or personal computer. You can access your documents, photos, videos and any other saved files from any device with internet access. With cloud services you can connect at home, work or on the go via a laptop, desktop, Smartphone or other handheld device.

Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction (Prabha, 2013). Those models and their relationship to essential characteristics of cloud computing.

Some of the world’s largest tech companies have launched cloud services, including Apple, Amazon, Microsoft and Google. These tech giants, along with some notable up-and-comers, provide several storage tier plans tailored for both consumers and businesses.

Deployment Models

A deployment model defines the purpose of the cloud and the nature of how the cloud is located. The NIST definition for the four deployment models is as follows

Private cloud

The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units). It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off premises (Peter & Timothy, 2012). The data is stored on-premises with the client or in client-dedicated facilities, and accessed over the client’s intranet. The management can be done either by the client or can be given (outsourced) to a service provider. Unlike the public model, data is comparatively secure behind enterprise firewalls. Because the storage space is not shared by other organizations, security and multi tenancy concerns are the same as in traditional IT. In this model, the client can also save significantly with storage consolidation and virtualization (Larry & Shivaramakrishnan, 2014).

Community cloud

Community cloud is when some clients with similar needs share an external private cloud (Maher & Najwa, 2014). The cloud infrastructure is provisioned for exclusives by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises (Peter & Timothy, 2012).

Public cloud

The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the cloud provider (Peter & Timothy, 2012). Data is stored on-premises with the cloud storage service provider and is accessed through network services. All the management tasks that are associated with storage, such as upgrading and replacing, are carried out by the storage service provider. Typically, this storage capacity is somewhat inexpensive because of economies of scale. But with data stored in the public domain, security and multitenancy are major areas of concern, which need to be evaluated in accordance with business requirements. (Larry and Shivaramakrishnan, 2014). These services are free or offered on a pay-per-use model. Generally, public cloud service providers like Amazon, Microsoft and Google own and operate the infrastructure and offer access only via Internet (Utpal & Majidul, 2013).

Hybrid cloud

The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds) (Peter & Timothy, 2012). Hybrid storage data is provisioned in a mixed private and public environment. For example, business-critical data (payroll processing, HR, finance) can be stored in a private cloud (to use the security and control over the data) and relatively less important data can be maintained in public cloud storage (Larry & Shivaramakrishnan, 2014).

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References:

1. Prabha Sharma (2013), ” Grid Computing Vs. Cloud Computing”, International Journal of Information and Computation Technology, Volume 3, Number 6, Pages 577-582
2. Peter Mell and Timothy Grance (2012), “The NIST Definition of Cloud Computing – Recommendations of the National Institute of Standards and Technology”, NIST, [Online] Available: http://csrc.nist.gov/publications/nistpubs/800-145/SP800-145.pdf , Retrieved 28 October 2014.
3. Larry Coyne, Shivaramakrishnan Gopalakrishnan, and John Sing (2014), “IBM Private, Public, and Hybrid Cloud Storage Solutions” [Online] Available: http://www.redbooks.ibm.com/redpapers/pdfs/redp4873.pdf, Retrieved 28 October 2014
4. Maher Alghali, Najwa Hayaati, and I. Roesnita (2014), “Challenges and Benefits of Implementing Cloud Based E-Learning in Developing Countries”, Proceeding of the Social Sciences Research ICSSR 2014, Pages 428-436
5. Utpal Jyoti Bora, and Majidul Ahmed (2013) E-Learning using Cloud Computing”, International Journal of Science and Modern Engineering (IJISME), ISSN: 2319-6386, Volume-1, Issue-2, Pages 9-18