In the previous sections, you learned about characteristics and services. Now, it is time to understand where these characteristics and services live and where the services are made available.
The most commonly used cloud deployment model is public. A public cloud means the service is run by an organization that is not a part of the organization to which the consumer belongs. The business objective of a public cloud provider, in most cases, is to make money. Another characteristic of a public cloud is that it is open to multiple consumers. This so-called multitenant usage is offered in data centers that are only accessible to employees working for the operator of the service.
A private cloud is the opposite of a public cloud. Services offered in a private cloud are typically consumed by a single organization. The infrastructure can be located either on premise or in a data center owned and operated by a service provider. The provider of the private cloud service is the IT department. It is also possible that the cloud management is outsourced to a vendor while the IT department handles the governance. A private cloud, in most cases, exists in large organizations that have frequent demands for new IT services. Organizations with a lot of software developers are use cases for private cloud, as developers have frequent requests for new virtual machines.
A community cloud is an offspring of a private cloud. This kind of cloud is used by a limited number of organizations that offer the same kind of service to their customers. Think about nonprofit organizations, schools, healthcare, or multiple municipalities sharing the same IT infrastructure. Saving on costs while delivering efficient IT services is the main goal of a community cloud.
A hybrid cloud is a combination of public cloud services and private clouds. It is not necessary to have a private cloud in order to use hybrid cloud. A hybrid cloud can be a combination of virtualized, on-premises data centers and public cloud services as well. Hybrid cloud can be done on the IaaS or SaaS level. Hybrid cloud can also be seen as a bridge between the public and private clouds, which enables moving workloads between those deployments based on policy, costs, and so on.
Enabling hybrid cloud became the main focus of many vendors such as VMware and Microsoft from 2012 onwards. They both share the vision that organizations will not move to the public cloud in one big bang. The public cloud, especially when using IaaS, still has a lot of uncertainties and many decision-makers do not know the risks and capabilities of a public cloud.
Hybrid cloud will be a way to get over the security and compliancy concerns that many organizations have on public cloud. Hybrid cloud allows them to enjoy the many benefits of public cloud, while still allowing control over the IT infrastructure and protecting critical services by running those on premise.