Cloud basics: public vs private clouds

Simon Edward • 9 December 2024

Public cloud, private cloud: what's the difference and why does it matter? Find out in our cloud basics guide.

Technology has a way of introducing terms that sound more unified than they are. Take "the internet". It's the internet. If you didn't know better, that definite article could imply a single dashboard or facility at the centre of all our online activities.

The same goes for "the cloud". Your holiday snaps may be in the cloud – but it's a different cloud from the one the government uses to store electoral data, say. "Cloud technologies" captures the diversity of the cloud far better than "the cloud", plain and simple.

Within cloud technologies, there are two main delivery models: private and public. The difference is simple, but the ramifications are not.

The basic difference between the two is that public clouds use shared infrastructure and private clouds use an organisation's own infrastructure.

If your organisation uses AWS for data storage, it's using the public cloud. The infrastructure is run and maintained by AWS and rented to you.

If, however, your organisation has a data centre of its own, it's using the private cloud. Those servers and cables are your company's responsibility and no one else's.

That's the difference – but why does it matter? It all comes down to control.

How is the cloud like electricity?

In today's digital marketplace, cloud technologies are as vital to day-to-day operations as electricity itself. But the similarity doesn't end there. Both the cloud and your electricity can be supplied in different ways.

Most of us do it the public way. We make monthly payments to an electricity provider. They maintain the infrastructure. We pay to use it. Simple.

But imagine you wanted more control over your electricity supply. For whatever reason, you want to get beneath the figurative bonnet and have a fiddle. Your best bet would be to install and use your own generator.

This is the electricity equivalent to the private cloud. Instead of relying on a public provider for your resources, you manage them yourself.

The key advantage of the private cloud is that it gives you greater administrative control. You never have to get on the phone or web chat and ask for support. The success or failure of your data centre is in your hands.

Private clouds are often used by businesses handling confidential information. After all, public clouds are, by nature, shared spaces. That doesn't mean another user can see your data. But it does mean that all that data, while separated, is resting in someone else's facility. It's understandable why government agencies, for instance, would want greater control of their data.

Still other companies want the best of both worlds. They achieve this through a delivery model known as the hybrid cloud.

Can you put private data in the public cloud?

Many enterprises still use on-prem data centres for their private data. But can you store private data in the public cloud?

The answer is "yes, but". Public clouds are a bit like banks. Each organisation's data is stored separately. Just as a bank doesn't throw all its customers' cash into one big vault, so cloud providers use a multi-tenancy model to protect data.

So, yes – you can put private data in the public cloud. Indeed, many companies do. However, it's important to understand the responsibilities that come with this.

Public cloud providers operate on the principle of shared responsibility. The cloud service provider is responsible for the physical security of the data. The customer, however, is responsible for keeping it safe with encryption, authentication, identity management and so on.

In other words, if you lose your data because your cloud provider's infrastructure goes down, it's their fault. If you lose your data because there was a hole in your security posture, it's yours.

It's also possible to run a private cloud in the public cloud. A virtual private cloud is an isolated environment within the public cloud where you can run tasks from your traditional data centre. This lets you maintain administrative control while availing yourself of the convenience of public cloud computing.

What is a hybrid cloud?

A hybrid car combines an internal combustion engine and one or more electric motors. Similarly, a hybrid cloud combines both public and private cloud environments.

The point is to achieve consistency. Many companies use a hybrid model as part of a long-term migration process. Front-end applications are moved to the public cloud, while sensitive data is kept on-premises.

The hybrid cloud has many use cases. One of the most persuasive from a business point of view is its elasticity. If your company experiences seasonal spikes, a hybrid cloud deployment lets you quickly and easily spin up new instances.

How is a hybrid cloud different from a multi-cloud?

A hybrid cloud combines the best of both worlds, combining public and private environments. By contrast, multi-cloud infrastructure is exclusively public – but it combines different clouds from different vendors.

Multi-cloud environments are now the norm, and they have two key advantages. First, they help avoid vendor lock-in. Secondly, they allow businesses to switch between cloud providers to get the best deal for their purposes.

There are also polyclouds. This is a multi-cloud setup where each cloud has a specific purpose: running AI on one cloud service provider, for instance, and your CRM on another.

Which type of cloud is right for me?

At Ascend Cloud Solutions, we believe your choice of infrastructure should be inseparable from your business needs. It all depends on what workloads you're running, the amount of sensitive data you hold, your existing cloud infrastructure, and more.

Your best bet is to speak to an experienced cloud consultant and talk through your options. There's no one-size-fits-all in cloud computing. Make sure you get a cloud environment that fits.

Are you looking for a consultant to help with your private or public cloud strategy? Ascend Cloud Solutions is an Ireland-based consultancy firm staffed by former VMware employees. We know the VMware stack like few others on Earth. Get in touch today to book a no-obligation consultation.