Public cloud vs. private cloud vs hybrid cloud

Cloud is an obvious choice for modern organizations looking to scale their computing capabilities. Less obvious is which type of cloud: public, private, or hybrid. Here’s a quick comparison of the benefits, drawbacks, and situational considerations of each cloud computing environment.

What’s the same?

Every cloud abstracts, pools, and shares scalable resources across a network. Every cloud type also enables cloud computing, which is the act of running workloads within that system. And every cloud is created using a unique mix of technologies, which almost always includes an operating system, some kind of management platform, and application programming interfaces (APIs)Virtualization and automation software can also be added to every kind of cloud for additional capabilities or increased efficiencies.

What’s different?

The differences between public clouds, private clouds, and hybrid clouds were once easily defined by location and ownership. But it’s just not that simple anymore. So while we compare the differences below, there are plenty of caveats.

Public clouds

Public clouds are cloud environments typically created from IT infrastructure not owned by the end user. Traditional public clouds always ran off-premises, but today’s public cloud providers have started offering cloud services on clients’ on-premise data centers. This has made location and ownership distinctions obsolete.

All clouds become public clouds when the environments are partitioned and redistributed to multiple tenants. Fee structures aren’t necessary characteristics of public clouds anymore, since some cloud providers (like the Massachusettes Open Cloud) allow tenants to use their clouds for free. The bare-metal IT infrastructure used by public cloud providers can also be abstracted and sold as Infrastructure-as-a-Service (IaaS), or it can be developed into a platform sold as a Platform-as-a-Service (PaaS).

Private clouds

Private clouds are loosely defined as cloud environments solely dedicated to a single end user, where the environment usually runs behind that user’s firewall. All clouds become private clouds when the underlying IT infrastructure is dedicated to a single customer with completely isolated access.

But private clouds no longer have to be sourced from on-prem IT infrastructure. Organizations are now building private clouds on rented, vendor-owned data centers located off-premises, which makes any location and ownership rules obsolete. This has also led to a number of private cloud subtypes, including:

Managed private clouds

Customers create and use a private cloud that’s deployed, configured, and managed by a third-party vendor. Managed private clouds are a cloud delivery option that helps enterprises with understaffed or underskilled IT teams provide better private cloud services and infrastructure.

Dedicated clouds

A cloud within another cloud. You can have a dedicated cloud on a public cloud  or on a private cloud. For example, an accounting department could have its own dedicated cloud within the organization’s private cloud.

Hybrid clouds

hybrid cloud is a seemingly single IT environment created from multiple other environments. The characteristics of hybrid clouds are complex and the requirements can differ, depending on whom you ask. For example, a hybrid cloud may need to include:

  • At least 1 private cloud and at least 1 public cloud
  • 2 or more private clouds
  • 2 or more public clouds
  • A bare-metal or virtual environment connected to at least 1 public cloud or private cloud

But every IT system becomes a hybrid cloud when apps can move in and out of multiple separate—yet connected—environments. At least a few of those environments need to be sourced from consolidated IT resources that can scale on demand. And all those environments need to be managed as a single environment using an integrated management and orchestration platform.

Which cloud should I use?

That depends on what you’re doing.

  • Workloads with high volume or fluctuating demands might be better suited for a public cloud.
  • Workloads with predictable use patterns might be better off in a private cloud.
  • Hybrid clouds are the catch-all, because any workload can be hosted anywhere.

Which cloud is safest?

That’s a loaded question.

  • Public clouds tend to have a wider variety of security threats due to multi-tenancy and numerous access points. Public clouds often split security responsibilities. For instance, infrastructural security can be the provider’s responsibility while workload security can be the tenant’s responsibility.
  • Private clouds are thought to be more secure because workloads usually run behind the user’s firewall, but that all depends on how strong your own security is.
  • Hybrid cloud security is made up of the best features of every environment, where users and admins can minimize data exposure by moving workloads and data across environments based on compliance, audit, policy, or security requirements.

Which cloud costs more?

Another loaded question.

  • You usually pay for what you use in a public cloud, though some public clouds (like the Massachusetts Open Cloud) don’t charge tenants.
  • Whoever set up a private cloud is usually responsible for purchasing or renting new hardware and resources to scale up.
  • Hybrid clouds can include any on-prem, off-prem, or provider’s cloud to create a custom environment that suits your cost requirements.

Which cloud has the best resources?

That depends on how you want to spend money. Do you want to incur capital expenses (CapEx) or operating expenses (OpEx)? This is the classic scale-up vs. scale-out question.

  • Public cloud users seem to have unlimited access to resources, but accessing those resources is usually an operational expense.
  • Deploying more private cloud resources requires buying or renting more hardware—all capital expenses.
  • Hybrid clouds give you the option of using operating expenses to scale out or capital expenses to scale up.

Author: Aditya Bhuyan

I am an IT Professional with close to two decades of experience. I mostly work in open source application development and cloud technologies. I have expertise in Java, Spring and Cloud Foundry.

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