Cloud computing is a growing trend that offers an innovative way to deliver software, data storage, and computing services. While the term cloud computing refers in general to the delivery of services on demand over a computer network, the National Institute for Science and Technology (NIST) has defined four different cloud computing deployment models; private cloud, community cloud, public cloud, and hybrid cloud.
This is the deployment model that most commonly described as cloud computing. In this model, all of the physical resources are owned and operated by a third party cloud computing provider. The provider services multiple clients that may consist of individuals or corporations utilizing these resources through the public Internet. Services can be dynamically provisioned and are billed based on usage alone. This model provides the highest degree of cost savings while requiring the least amount of overhead.
A private cloud describes computer services delivered to a single organization. This model shares many of the characteristics of a traditional client-server architecture, while integrating features associated with other models cloud computing. Like other cloud models, services are delivered on demand from a distributed infrastructure. Unlike the client-server computing model, users do not access a particular resource in a known location and there are minimal hardware and software requirements for their client computer. The cloud computing resources may be situated on or off-site, and they can either be managed in-house or by a third party. This model addresses the security and privacy concerns that are inherent in other cloud computing models.
A community cloud contains features of the public and private cloud models. Like a public cloud, the community cloud may contain software, data storage, and computing resources that are utilized by multiple organizations. Where this model differs from the public model is that the infrastructure is only utilized by a group of organizations that are known to each other. Similarly to a private cloud, these organizations are responsible for the operation of their own infrastructure. The community cloud model can provide greater cost savings than the private cloud while offering some of its security features. This model is best suited for organizations that share common requirements such as security or legal compliance policies. It can be managed by the member organizations or by a third party provider.
The hybrid cloud computing model employs aspects of all of the other cloud models and it is the most common method of cloud deployment within a large organization. A company may use internal resources in a private cloud maintain total control over its proprietary data. It can then use a public cloud storage provider for backing up less sensitive information. At the same time, it might share computing resources with other organizations that have similar needs. By combining the advantages of the other models , the hybrid model offers organizations the most flexibility.