December 28, 2015

Semantics: "Public," "Private," and "Hybrid" in Cloud Computing, Part II

December 28, 2015

Welcome back! In the second post in this two-part series, we’ll look at the third definition of “public” and “private,” and we’ll have that broader discussion about “hybrid”—and we’ll figure out where we go after the dust has cleared on the semantics. If you missed the first part of our series, take a moment to get up to speed here before you dive in.

Definition 3—Control: Bare Metal v. Virtual

A third school of thought in the “public v. private” conversation is actually an extension of Definition 2, but with an important distinction. In order for infrastructure to be “private,” no one else (not even the infrastructure provider) can have access to a given hardware node.

In Definition 2, a hardware node provisioned for single-tenancy would be considered private. That single-tenant environment could provide customers with control of the server at the bare metal level—or it could provide control at the operating system level on top of a provider-managed hypervisor. In Definition 3, the latter example would not be considered “private” because the infrastructure provider has some level of control over the server in the form of the virtualization hypervisor.

Under Definition 3, infrastructure provisioned with full control over bare metal hardware is “private,” while any provider-virtualized or shared environment would be considered “public.” With complete, uninterrupted control down to the bare metal, a user can monitor all access and activity on the infrastructure and secure it from any third-party usage.

Defining “public cloud” and “private cloud” using the bare metal versus virtual delineation is easy. If a user orders infrastructure resources from a provider, and those resources are delivered from a shared, virtualized environment, that infrastructure would be considered public cloud. If the user orders a number of bare metal servers and chooses to install and maintain his or her own virtualization layer across those bare metal servers, that environment would be a private cloud.

“Hybrid”

Mix and Match

Now that we see the different meanings “public” and “private” can have in cloud computing, the idea of a “hybrid” environment is a lot less confusing. In actuality, it really only has one definition: A hybrid environment is a combination of any variation of public and private infrastructure.

Using bare metal servers for your database and virtual servers for your Web tier? That’s a hybrid approach. Using your own data centers for some of your applications and scaling out into another provider’s data centers when needed? That’s hybrid, too. As soon as you start using multiple types of infrastructure, by definition, you’ve created a hybrid environment.

And Throw in the Kitchen Sink

Taking our simple definition of “hybrid” one step further, we find a few other variations of that term’s usage. Because the cloud stack is made up of several levels of services—Infrastructure as a Service, Platform as a Service, Software as a Service, Business Process as a Service—“hybrid” may be defined by incorporating various “aaS” offerings into a single environment.

Perhaps you need bare metal infrastructure to build an off-prem private cloud at the IaaS level—and you also want to incorporate a managed analytics service at the BPaaS level. Or maybe you want to keep all of your production data on-prem and do your sandbox development in a PaaS environment like Bluemix. At the end of the day, what you’re really doing is leveraging a “hybrid” model.

Where do we go from here?

Once we can agree that this underlying semantic problem exists, we should be able to start having better conversations:

  • Them: We’re considering a hybrid approach to hosting our next application.
  • You: Oh yeah? What platforms or tools are we going to use in that approach?
  • Them: We want to try and incorporate public and private cloud infrastructure.
  • You: That’s interesting. I know that there are a few different definitions of public and private when it comes to infrastructure…which do you mean?
  • Them: That’s a profound observation! Since we have our own data centers, we consider the infrastructure there to be our private cloud, and we’re going to use bare metal servers from SoftLayer as our public cloud.
  • You: Brilliant! Especially the fact that we’re using SoftLayer.

Your mileage may vary, but that’s the kind of discussion we can get behind.

And if your conversation partner balks at either of your questions, send them over to this blog post series.

-@khazard

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