Cloud deployment models define the implementation of the cloud infrastructure within an organization. They are divided into four broad categories namely Private cloud, Public cloud, Community cloud and Hybrid cloud. Based on the needs of an organization, these implementations can help save capital cost and also eliminate the operating cost of these cloud infrastructures. The National Institute of Standards and Technology (NIST) define the framework of these models. The model defines the access to cloud infrastructure, the extent of which is defined by the service contract and the target audience of the cloud.
The Private cloud deployment model is the most expensive among its peers. The cloud serves only its designated organization and is not shared among others. The users are given privilege access using highly secure keys and often use external clients like VPN to log into the cloud. This also provides the client with complete access to the cloud infrastructure thereby enabling them to customize the platform to their specific needs. In most cases, these clouds serve different business units within an organization, which are functionally different. The customer is given the choice to either have the cloud framework on the premises or have a third party manage it at a different location. A caveat in this model is the potential threat to data security in the cloud in the event of a natural disaster and internal data theft. The organization must use a cloud backup and cloud storage company to secure the sensitive data to protect itself against any mishaps. The maintenance of the cloud will be the responsibility of the customer, and not the cloud service provider.
The public cloud model is the most popular and serves a large number of users. In this model, the customer shares the cloud infrastructure with other customers. The operating and maintenance costs of the cloud are the responsibility of the cloud service provider. The cloud-hosting provider charges a fee, using a license model of pay per user. This benefits the organization monetarily as it eliminates the need for spending on operational IT costs. This model suits small businesses, which require load balancing and management, hosting SaaS applications, using interim infrastructure for development and testing of their applications. Most service providers are transparent with the physical locations of the datacenters. They provide the user with various levels of security packages to the public cloud users, based on subscription models.
The most cost effective cloud model is the community model. This cloud infrastructure is shared by business with a common interest or objective. The cost is amortized over all these different businesses. The classic example for this model is the cloud that would be used by state run organizations, which require sharing data of the local demography between the various departments. The service provider takes care of the infrastructure maintenance in this model.
The hybrid model is a combination of two or more of the above-mentioned models. While it keeps the cloud independent, it provides easy data portability between clouds. This enables organizations to partition their data based on the sensitivity of the information and host them on various clouds, striking a perfect balance between privacy and cost effectiveness.