Understanding cloud deployment models
When it comes to deploying cloud services for your organization, you need to consider which deployment model will suit your business. The decision will be taken based on several factors, such as the industry you are in, compliance and regulatory issues, and also cost management and flexibility of configuration.
There are three primary models of deployment, listed as follows:
- Public cloud
- Private cloud
- Hybrid cloud
These models are represented in the following diagram:
Figure 1.3 – Cloud deployment models
Let's look at each model in a little more detail.
Public cloud
A public cloud is a cloud deployment model in which a business consumes IT services from a third-party vendor, such as AWS, over the internet. This is the most popular model of cloud computing due to the vast array of services on offer. Public cloud providers such as AWS are in the business of delivering IT services across all industry verticals and for businesses of all sizes.
Public cloud services are generally paid for on a pay-as-you-go model and can help your organization move away from a CAPEX of mode of investment in IT to an OPEX mode. This frees up precious capital for more important investment opportunities. Services offered by public cloud vendors will include free services, subscription-based, or on-demand pay-as-you-go, where you are charged based on how much you consume. Providers of public cloud services are also able to offer greater scalability and agility that would otherwise have been too expensive to achieve on your own.
With a public cloud model, customers are offered a self-service capability and access to management consoles and command-line interfaces, as well as having API access to configure and consume the services on offer.
Private cloud
By contrast, a private cloud is a cloud deployment model in which your business procures, installs, configures, and manages all the necessary infrastructure and software components in-house. This may sound very similar to traditional on-premises IT. However, the cloud element of it comes from the fact that additional management software is usually deployed to allow different parts of the business to carry out self-service tasks in provisioning compute, storage, network, and software services from an available catalog of services.
While public cloud providers offer their services to all businesses across the globe and the services are therefore publicly available, a private cloud is designed solely for your business, where you will not be sharing underlying compute resources with anyone external to your organization.
A private cloud is highly customizable to suit the needs of your organization, giving maximum control on key areas such as designing security and infrastructure configuration options. This does not necessarily mean that a private cloud provider (for example, Red Hat OpenStack) is more secure than a public cloud provider. Public cloud providers such as AWS invest vast amounts of money to design security features for the services they offer—features that may be cost-prohibitive if an organization tried to implement them on its own.
Hybrid cloud
This is a combination of IT services deployed both on-premises (and managed solely by your business) and integrated with one or more third-party cloud providers.
Many companies that venture into the public cloud generally start with some form of hybrid model. Often, businesses will move/migrate services to the public cloud to reduce CAPEX investment as they opt for a pay-as-you-go model for the consumption of IT services. An example of this is where companies may need to increase the number of servers deployed for their applications, and rather than procuring more expensive physical hardware, they can set up network connectivity between on-premises infrastructure and the public cloud provider, where they would spin up those additional servers as required. Connectivity options between an on-premises environment and a cloud provider can include setting up a secure Internet Protocol Security (IPsec) virtual private network (VPN) tunnel over the public internet, or even establishing a dedicate fiber-based connection, bypassing the public internet altogether and benefiting from greater bandwidth.
A hybrid cloud is generally also used to help start off your disaster recovery (DR) projects, which often need network communication between the private cloud infrastructure and the services offered by public cloud vendors where the DR solution will be hosted. This enables replication of on-premises data and applications to the DR site, hosted with vendors such as AWS.
Hybrid cloud deployments can also help businesses to start testing out new cutting-edge technologies or adopt a phased migration approach to ensure minimum interruption to normal business functions while the migration is underway. In addition, HA solutions can also be implemented. To cite an example, if the on-premises infrastructure is experiencing downtime, consumers of those services can be redirected to replica services hosted with the public cloud provider.