Six Criteria for Evaluating the Pros and Cons of Public vs. Private Cloud

Posted by Annie Eissler on October 18, 2018

An estimated 97 percent of organizations use cloud services today, according to McAfee, and Cisco forecasts cloud workloads nearly tripling between 2016 and 2021. Cloud computing has clearly gone mainstream. Yet the debate goes on: Which is best, public or private?

The public cloud market continues to expand. Gartner forecasts 21 percent growth in 2018 from 2017, and 17.3 percent growth in 2019. At the same time, the demand is growing for private cloud services. IDC found that 56 percent of cloud providers surveyed delivered their services over the public cloud — and almost as many used the private cloud, along with other solutions such as colocation.

If you’re evaluating your cloud strategy, consider the following criteria as part of your decision-making formula.


Public-cloud providers typically offer at least some degree of customization, as well as the ability to quickly scale up or down based on your needs. If you need even more flexibility, a private-cloud solution may be a better choice because it’s tailored specifically to your business. You get better control of your infrastructure and resource allocation.


Gone are the days when fear about data security was the biggest barrier to cloud adoption. Leading players like AWS and Azure have been investing heavily in the security of their public cloud. Their enterprise-class firewalls and highly secure facilities provide robust protection for your data, but that protection has limitations.

When you host in a private environment, you get additional layers of security. Private hosting limits both where your cloud can be accessed from and who can access it. And since you don’t have to transfer the workload over the public internet, you’re drastically decreasing the chance of your data being compromised while it travels “in the wild.”


When you’re using a public-cloud provider, you’re not likely to know where your data resides. You have little knowledge of what exactly goes on “behind” the cloud. The private cloud, on the other hand, gives you complete visibility of your infrastructure — you can see beyond the “front door.”


A cloud outage is just as big a concern as security. The massive 2017 AWS outage that resulted from the distributed denial-of-service-attack on DNS vendor Dyn was an eye-opening example of the chaos from the outage of a big cloud provider. One recent report geared to insurance companies estimated that an incident that takes down a major cloud provider for three to five days in the United States could cost businesses as much as a staggering $19 billion.

Cloud outages are rare, and both private and public cloud providers use multiple redundancies for high reliability. The advantage of a private-cloud vendor is that you typically get guaranteed up time.


Factors that impact the performance of your workload include distance and resource availability. With the public cloud, you share the resources with many other customers. This impacts how well your environment performs at any given time.

In the single-tenant model of the private cloud, you have dedicated resources for your hardware, network, computing, etc. Additionally, you could reduce latency by choosing a data center in your geographic area. A public provider doesn’t give you that option.

Total Cost of Ownership

Often times, businesses opt for the public cloud because it is more cost-effective in the short term. There’s no argument that the economies of scale are a benefit of the public cloud. In the long term, however, the additional costs of providing security and compliance, as well as heavy processing workloads and managing your solution, could significantly increase your TCO.

When you weigh the pros and cons of public vs. private cloud, you may decide that one is better for some of your workloads while the other has advantages in certain scenarios. Once you analyze factors beyond costs and platform capabilities, you need to consider which solution is the best long-term, strategic approach — or whether you should take advantage of both platforms by choosing a hybrid cloud approach.