Cloud computing deployment models

Cloud computing as much about learning the architecture as it is about the different deployment options that we have. We need to know the different ways our cloud infrastructure can be kept open to the world and do we want to restrict it. There are three ways of cloud computing and its deployment:

• Private cloud
• Public cloud
• Hybrid cloud

Private cloud

Private cloud services are built specifically when companies want to hold everything to them. It provides the users with customization in choosing hardware, in all the software options, and storage options. This typically works as a central data center to the internal end users. This model reduces the dependencies on external vendors. Enterprise users accessing this cloud may or may not be billed for utilizing the services.

Private cloud changes how an enterprise decides the architecture of the cloud and how they are going to apply it in their infrastructure. Administration of a private cloud environment can be carried by internal or outsourced staff.

Common private cloud technologies and vendors include the following:

• VMware: https://cloud.vmware.com
• OpenStack: https://www.openstack.org
• Citrix: https://www.citrix.co.in/products/citrix-cloud
• CloudStack: https://cloudstack.apache.org
• Go Grid: https://www.datapipe.com/gogrid

With a private cloud, the same organization is showing itself as the cloud consumer as well as the cloud provider, as the infrastructure is built by them and the consumers are also from the same enterprise. But in order to differentiate these roles, a separate organizational department typically assumes the responsibility for provisioning the cloud and therefore assumes the cloud provider role, whereas the departments requiring access to this established private cloud take the role of the cloud consumer:

Public cloud

In a public cloud deployment model, third-party cloud service provider often provide the cloud service over the internet . Public cloud services are sold with respect to demand and by a minute or hour basis. But if you want, you can go for a long term commitment for up to five years in some cases, such as renting a virtual machine. In the case of renting a virtual machine, the customers pay for the duration, storage, or bandwidth that they consume (this might vary from vendor to vendor).

Major public cloud service providers include:

• Google Cloud Platform: https://cloud.google.com
• Amazon Web Services: https://aws.amazon.com 
• IBM: https://www.ibm.com/cloud
• Microsoft Azure: https://azure.microsoft.com
• Rackspace: https://www.rackspace.com/cloud

The architecture of a public cloud will typically go as follows:

Hybrid cloud

The next and the last cloud deployment type is the hybrid cloud. A hybrid cloud is an amalgamation of public cloud services (GCP, AWS, Azure likes) and an on-premises private cloud (built by respective enterprise). Both on-premise and public have their roles here. On-premise are more for mission-critical applications, whereas public cloud manage spikes in demand. Automation is enabled between both the environment. 

The following figure shows the architecture of a hybrid cloud:

The major benefit of a hybrid cloud is to create a uniquely unified, superbly automated, and insanely scalable environment that takes the benefit of everything a public cloud infrastructure has to offer, while still maintaining control over mission-critical vital data.

Some common hybrid cloud examples include:

• Hitachi hybrid cloud: https://www.hitachivantara.com/en-us/solutions/hybrid-cloud.html
• Rackspace: https://www.rackspace.com/en-in/cloud/hybrid
• IBM: https://www.ibm.com/it-infrastructure/z/capabilities/hybrid-cloud
• AWS: https://aws.amazon.com/enterprise/hybrid

Differences between the private cloud, hybrid cloud, and public cloud models

The following tables summarizes the differences between the three cloud deployment models:

	Private	Hybrid	Public
Definition	A cloud computing model in which enterprises uses its own proprietary software and hardware. And this is specifically limited to its own data centre. Servers, cooling system, and storage - everything belongs to the company.	This model includes a mixture of private and public cloud. It has a few components on-premises, private cloud and it will also be connected to other services on public cloud with perfect orchestration.	Here, we have a complete third-part or a company that lets us use their infrastructure for a given period of time. This is a pay-as-you-use model. General public can access their infrastructure and no in-house servers are required to be maintained.
Characteristics	Single-tenant architecture On-premises hardware Direct control of the hardware	Cloud bursting capacities Advantages of both public and private cloud Freedom to choose services from multiple vendors	Pay-per use model Multi-tenant model
Vendors	HPE, VMWare, Microsoft, OpenStack	Combination of public and private	Google Cloud Platform, Amazon Web Services, Microsoft Azure