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Cloud computing from Service Provider point of view
Cloud Deployment Models :
Public, Private, Community and Hybrid
Provider that delivers any Cloud solutions is responsible for maintaining whole hardware infrastructure and depends on type of deployed service solutions for software also. This article will be devoted to Cloud models offered by Providers and which one of them is suitable for particular companies.
A cloud deployment model provides a basis for how cloud infrastructure is built, managed, and accessed. There are distinguished the four primary cloud deployment models listed below:
Public cloud
Private cloud
Hybrid cloud
Community cloud
Each cloud deployment model may be used for any of the cloud service models: IaaS, PaaS, and SaaS.
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.Public cloud services may be free, subscription-based, or provided on a pay-per-use model. A public cloud provides the benefits of low up-front expenditure on IT resources and enormous scalability. However, some concerns for the consumers include network availability, risks associated with multi-tenancy, visibility and control over the cloud resources and data, and restrictive default service levels.
PRIVATE CLOUD
The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (for example, 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.Many organizations may not wish to adopt public clouds due to concerns related to privacy, external threats, and lack of control over the IT resources and data. When compared to a public cloud, a private cloud offers organizations a greater degree of privacy and control over the cloud infrastructure, applications, and data. There are two variants of private cloud: on-premise and externally-hosted, as shown in figure 1 and figure 2 respectively on the slide. The on-premise private cloud is deployed by an organization in its data center within its own premises. In the externally-hosted private cloud (or off-premise private cloud) model, an organization outsources the implementation of the private cloud to an external cloud service provider. The cloud infrastructure is hosted on the premises of the provider and may be shared by multiple tenants. However, the organization’s private cloud resources are securely separated from other cloud tenants by access policies implemented by the provider.
COMMUNITY CLOUD
The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (for example, 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.The organizations participating in the community cloud typically share the cost of deploying the cloud and offering cloud services. This enables them to lower their individual investments. Since the costs are shared by a fewer consumers than in a public cloud, this option may be more expensive. However, a community cloud may offer a higher level of control and protection than a public cloud. As with the private cloud, there are two variants of a community cloud: on-premise and externally-hosted.In an on-premise community cloud, one or more organizations provide cloud services that are consumed by the community. The cloud infrastructure is deployed on the premises of the organizations providing the cloud services. The organizations consuming the cloud services connect to the community cloud over a secure network. The figure on the slide illustrates an example of an on-premise community cloud.
In the externally-hosted community cloud model, the organizations of the community outsource the implementation of the community cloud to an external cloud service provider. The cloud infrastructure is hosted on the premises of the provider and not within the premises of any of the participant organizations. The provider manages the cloud infrastructure and facilitates an exclusive community cloud environment for the organizations.
The IT infrastructure of each of the organizations connects to the externally-hosted community cloud over a secure network. The cloud infrastructure may be shared with multiple tenants. However, the community cloud resources are securely separated from other cloud tenants by access policies implemented by the provider.
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 by standardized or proprietary technology that enables data and application portability (for example, cloud bursting for load balancing between clouds.) The figure on the slide illustrates a hybrid cloud that is composed of an on-premise private cloud deployed by enterprise P, and a public cloud serving enterprise and individual consumers in addition to enterprise P.
The hybrid cloud has become the model of choice for many organizations. Some use cases of the hybrid cloud model are described below.
Cloud bursting: Cloud bursting is a common usage scenario of a hybrid cloud. In cloud bursting, an organization uses a private cloud for normal workloads, but optionally accesses a public cloud to meet transient higher workload requirements. For example, an application can get additional resources from a public cloud for a limited time period to handle a transient surge in workload.
Web application hosting: An organization may use the hybrid cloud model for web application hosting. The organization may host mission-critical applications on a private cloud, while less critical applications are hosted on a public cloud. By deploying less critical applications in the public cloud, an organization can leverage the scalability and cost benefits of the public cloud. For example, e-commerce applications use public-facing web assets outside the firewall and can be hosted in the public cloud.
Packaged applications: An organization may also migrate standard packaged applications, such as email and collaboration software out of the private cloud to a public cloud. This frees up internal IT resources for higher value projects and applications.
Application development and testing: An organization may also use the hybrid cloud model for application development and testing. An application can be tested for scalability and under heavy workload using public cloud resources, before incurring the capital expense associated with deploying it in a production environment. Once the organization establishes a steady-state workload pattern and the longevity of the application, it may choose to bring the application into the private cloud environment.
During writing this article I used EMC and NIST (National Institute of Standards and technology ) publications. All pictures originate from EMC.