So commonly used, that boundaries get blurry.
Cloud is everywhere, where you think it is, and mostly where you do not imagine it is, and in
In this industry, we manage terms with great flexibility, mostly because we use them in a context that provides the information which maybe we are not offering while not using the right
I was recently challenged to get the right definition of the different types of cloud we are using in our daily job as IT pros offering solutions to customers. My surprise was that even terms which we might have thought were clear for everybody, once we scratched the surface and details flourished, they happened to be also open for discussion. Nothing worse than an internal discussion in front of the customer about what Hybrid Cloud is, or Private Cloud, or what the difference between Multi-Cloud or Hybrid Cloud is. So, I decided to investigate and search for different sources about the meaning of these four terms and try to get a common perspective which would allow us all to understand the same when we use the same terms. Here is the result of that exercise. I hope you find it as useful as we did.
Cloud Deployment Methods
Probably the confusion starts when mixing different perspectives about cloud: Private, Public and Hybrid Cloud terms, refer to the deployment method used to build a specific cloud, while Multi-Cloud is a reference to the number of clouds used (many of them); this last term plays in another league, and should not be mixed with the other three. I like this Wikipedia approach on this topic. So, we have 3 cloud deployment methods:
- Private Cloud
- Public Cloud
- Hybrid Cloud
Let’s now review these concepts.
Private Cloud
Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third party, and hosted either internally or externally.
It is not relevant who the owner of the cloud infrastructure is, or where the infrastructure is located. The definition is focused on the fact that the infrastructure is operated for a single company, this is the key
Curious about what well-reputed sources say about it?
| Source | Private Cloud Definition | Reference |
|---|---|---|
| Gartner | Private cloud computing is a form of cloud computing that is used by only one organization, or that ensures that an organization is completely isolated from others. | Gartner’s glossary |
| Wikipedia | Private cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third party, and hosted either internally or externally. | Wikipedia |
| TechTarget | Private Cloud (Internal cloud or corporate cloud) Private cloud is a type of cloud computing that delivers similar advantages to public cloud, including scalability and self-service, but through a proprietary architecture. Unlike public clouds, which deliver services to multiple organizations, a private cloud is dedicated to the needs and goals of a single organization. | TechTarget |
Public cloud
| A public cloud is one where scalable and elastic IT-enabled capabilities are provided as a service to external customers using Internet technologies |
The key concept is the the capabilities are provided as a service external to the customers ans using internet.
Example:
The MSP manages the IT infrastructure deployed in Azure, AWS or GCP.
What do other sources say?
| Source | Public Cloud Definition | Reference |
|---|---|---|
| Gartner | Gartner defines public cloud computing as a style of computing where scalable and elastic IT-enabled capabilities are provided as a service to external customers using Internet technologies—i.e., public cloud computing uses cloud computing technologies to support customers that are external to the provider’s organization. | Gartner’s glossary |
| Wikipedia | A cloud is called a “public cloud” when the services are rendered over a network that is open for public use. Technically there may be little or no difference between public and private cloud architecture, however, security consideration may be substantially different for services. | Wikipedia |
| TechTarget | A public cloud is one based on the standard cloud computing model, in which a service provider makes resources, such as virtual machines (VMs), applications or storage, available to the general public over the internet. Public cloud services may be free or offered on a pay-per-usage model. | TechTarget |
Hybrid cloud
| Hybrid cloud is a composition of two or more clouds (private and public) that remain distinct entities but are bound together, offering the benefits of multiple deployment models. |
The key here is that at least a private cloud AND and public cloud are working together.
Example:
What do other sources say?
| Source | Hybrid Cloud Definition | Reference |
|---|---|---|
| Gartner | “Hybrid cloud computing refers to policy-based and coordinated service provisioning, use and management across a mixture of internal and external cloud services. | https://blogs.gartner.com/it-glossary/hybrid-cloud-computing/” |
| Wikipedia | Hybrid cloud is a composition of two or more clouds (private or public) that remain distinct entities but are bound together, offering the benefits of multiple deployment models. | Wikipedia |
| TechTarget | Hybrid cloud is a cloud computing environment that uses a mix of on-premises, private cloud and third-party, public cloud services with orchestration between the two platforms. By allowing workloads to move between private and public clouds as computing needs and costs change, hybrid cloud gives businesses greater flexibility and more data deployment options. | TechTarget. |
| IDG | “once you have resources both on premises and on a public cloud, you are already running a hybrid cloud environment (or even multi-cloud, if you use more than one cloud provider)”. | “What does hybrid cloud mean in practice?“. Dec 2017 |
Other Cloud classifications
Multi-Cloud
Multi-Cloud is part of another cloud classification, based on the number of different clouds used.
| Multi-cloud usually refers to any mix of public clouds |
Does it mean that Multi-Cloud and Multi-Public-Cloud are the same? In my opinion, yes, they are usually the same.
What about a Multi-Cloud based on private clouds?
And what about a Multi-Cloud with a private and some public clouds? In that case, we have a hybrid cloud, as defined above.
Example:
A MSP manages the IT infrastructure deployed in Azure and AWS, for Customer Z
What do other sources say?
| Source | Multi Cloud Definition | Reference |
|---|---|---|
| Gartner | No entries available in Gartner’s glossary | – |
| Wikipedia | Multi-cloud is the use of multiple cloud computing services in a single heterogeneous architecture to reduce reliance on single vendors, increase flexibility through choice, mitigate against disasters, etc. It differs from | Wikipedia |
| TechTarget | A multi-cloud strategy is the use of two or more cloud computing services. While a multi-cloud deployment can refer to any implementation of multiple software as a service (SaaS) or platform as a service (PaaS) cloud offerings, today, it generally refers to a mix of public infrastructure as a service (IaaS) environments, such as Amazon Web Services and Microsoft Azure. | TechTarget |
| IDG | No entries at IDG | – |
Summary
3 main cloud deployment models:
- Private cloud
- Public cloud
- Hybrid cloud
And a different concept, Multi-cloud, which refers to multiple cloud entities (mostly all public ones) rather than multiple deployment modes (public, private, legacy).
The graph below shows them all.
