All clouds are not created equal, and generic references to cloud may be confusing. Just like all automobiles are not the same, not are all clouds the same.
There are essentially three types of clouds:
- Private
- Public
- Hybrid
Each has its own benefits and drawbacks as will be discussed below, and sometimes the confusion related to clouds is based on lack of a clear definition.
Private Cloud
Private cloud refers to on-premises infrastructure that may be housed within the enterprise or within a segregated space in a co-located data center. The servers and hypervisor resources deployed in this type of data center are dedicated solely to a single enterprise. Within a private cloud environment, IT is fully responsible for the hardware, software, networking, monitoring, and maintenance.
Private clouds have the benefit of being highly customizable. If an organization has unique requirements, IT has full authority to alter computing systems as they see fit. The downside is that costs can spiral out of control, especially within organizations that are decentralized.
With a private cloud, expansion and contraction present challenges. For example, if additional resources are required in order to address a busy season or fewer resources are needed during slow times, the enterprise must provision equipment based on peak requirements, plus an element of redundancy. As such, the total cost of ownership is higher due to idle resources.
Disaster recovery is more complex and expensive with a private cloud infrastructure. Duplicate system resources are required at a secondary site that go unused during normal operations. As a result, the costs for a disaster recovery site with a private cloud cost are doubled.
Public Cloud
Public cloud is gaining in popularity as providers–such as Azure, Amazon Web Services, and Google Cloud Services–offer fixed costs for hosted resources. Enterprises have a clear understanding of the costs for utilizing each type of resource and can accurately predict monthly utilization fees. In addition, there are no surprise costs for maintenance or equipment replacement.
Referring to the example of an enterprise that experiences peak and slow seasons, public cloud services are optimal from a cost standpoint because resources are only enabled when necessary. This can represent massive savings.
By offering compute resources within a shared infrastructure, complexity is reduced and scalability is improved. IT staff no longer needs to request and order new hardware, place it in server racks, install networking equipment, ensure proper cooling levels in the data center, and similar work effort. Instead, an IT professional just selects the desired resource from an administrative interface, and the resource is quickly deployed. Public clouds enable IT to be extremely agile.
When testing new applications or processes, running a Proof of Concept (PoC) in a cloud environment is fast and easy. By simply designating the compute resources, testing can commence in short order to prove or disprove a new concept.
Public cloud systems require a new skill set for IT staff. While the administrative interfaces are generally intuitive, there are many unique technology features to each public cloud that must be absorbed by the IT staff. Also, each public cloud uses slightly different terminology and processes, so there is a learning curve for each public cloud.
A key downside to a public cloud infrastructure is lack of control of backend systems. When an entire site or public cloud provider experience issues, all tenants may be impacted. While Service-Level Agreements (SLAs) guarantee high uptime, system interruptions do occur from time to time.
Hybrid Cloud
Private clouds and public clouds each have unique benefits, and enterprises can opt to take advantage of the best of each by adopting a hybrid cloud solution. While it may take a bit more work effort to ensure full integration and access, the flexibility, cost, and reliability gains are significant.
For example, an enterprise may elect to continue operating an on-premises data center and utilize a public cloud for disaster recovery. With this solution, a secondary site does not need to be allocated. Thus, DR site resources are not billed until needed, so the total cost of ownership is significantly lower.
One downside to a hybrid cloud environment is that IT staff must be thoroughly familiar with both clouds and be able to determine which cloud is best suitable for each circumstance. This may necessitate additional training and perhaps even more IT staff.
Which Cloud is Best?
Although hybrid is often selected as the optimal solution, such is not always the case. Most organizations have moved or are in the process of moving at least some of their compute infrastructure to a public cloud. However, some are choosing to continue exclusively with a private cloud, and others are moving all system resources to a public cloud.
Cost and functionality are key drivers in determining which cloud is most suitable. Because all clouds are not created equal, each enterprise must delve into the benefits of each type of cloud to determine whether private, public, or hybrid cloud is the best solution.
