3.3 vCloud Definitions
vCAT uses the terms private vCloud, public vCloud, and hybrid vCloud, based on a specific set of definitions provided by NIST.
Private cloud:
A private vCloud (also known as an internal vCloud.) operates on private networks, where resources are accessible behind the firewall by a single company. In many cases, all the tenants share one legal entity. For example, a university might offer IaaS to its medical and business schools, or a company might do the same for various groups or business units. The private vCloud can be managed by the enterprise and hosted on premise or operated on a dedicated infrastructure provided by a vCloud service provider or systems integrator. In any case, a private vCloud must conform to the organizational security constraints.
Public cloud:
A public vCloud offers IT resources as a service through external service providers and is shared across multiple organizations or the Internet. This can be viewed as a vCloud infrastructure that is operated by one organization for use by multiple, legally separated organizations.
A public vCloud is provisioned for open access and might be owned, managed, and operated by one or more entities.
A public vCloud provider might also support a private, community, or hybrid vCloud.
Hybrid cloud:
A hybrid vCloud combines the benefits of the private and the public vCloud, with flexibility and choice of deployment methods.
A hybrid vCloud consists of multiple, linked vCloud infrastructures. These distinct vCloud infrastructures can be private, community, or public, they but must meet a set of requirements defined by the providers and agreed to by the consumers. Connecting these vCloud instances requires data and application mobility as well as management.
When load-balancing between vCloud instances (cloud bursting), use a consistent monitoring and management approach when migrating an application or data workload. For the theory behind cloud bursting see the document titled Cloud Bursting.
Community cloud:
A Community vCloud is a specific public vCloud use case where the cloud is shared, and typically owned, by a group of organizations with a common set of requirements. In many cases, the organizations also include some level of legal separation. Community vCloud resources are shared, with some parts under central control and other parts with defined autonomy. A vCloud built for government, education, or healthcare might be an example of a community vCloud.
A community vCloud can be offered by a traditional service provider, by a member of the community, or by a third-party vendor and hosted on one or more sites. It can be placed on-premise at one or more of the organizations’ sites, off-premise at a vCloud provider site, or both on- and off-premise.