Public, Private, and Hybrid Oh My: When to Use Which Cloud

Cloud roundabout

Public cloud, private cloud, hybrid cloud — which type of cloud is right for your organization?

At the most basic level, it’s all about the platform requirements — do you know your platform requirements? What about the application requirements?  Are there any specific capabilities you must deliver to your consumers?

I believe the project or application should drive the platform capabilities, and not the other way around. Below, I’ve described each cloud type and why organizations may use each one.

Public Cloud

A public cloud is a platform that provides computing, storage and/or networking capabilities in a multi-tenant format open to multiple organizations. It is the UberPool of the internet.  Public cloud is super convenient, easy to use and has its place in many organization’s portfolio, for sure.

Practical use case for public cloud include:

  • single application development and testing
  • supplementing private cloud resources
  • quick on-demand disposable resources
  • true charge-per-use scenarios

Why use it and the facts:

  1. It’s easy — create an account, provide a credit card and start consuming. Boom! No physical hardware consideration or management needed. Just use it/dispose of it as you wish.
  2. Because you’re sharing resources with someone you may not know, you might not want to place applications with sensitive data on it, just as if you were in a UberPool, you wouldn’t hand the guy next to you your wallet.
  3. Can be an appealing choice, until you realize you can easily lost track of your spend.  If the bill keeps rising, you may get tired of dodging your CFO in the hallways.

Private Cloud

Like the public cloud model from a base capabilities standpoint, but a private cloud is solely dedicated to your organization. To extend the analogy, it’s going UberSelect all the way! Still very convenient but does involve more planning. Grants you complete infrastructure control from performance, security and compliance points of view.

Practical use case for private cloud include:

  • lifecycle management for multiple applications
  • e-commerce based platform
  • provides ‘steady state’ resources
  • provides persistent resources for hosting applications
  • makes resources available across multiple business units that need isolation
  • hybrid application deployments — ability to interact with dedicated physical hardware from the private cloud.

Why use it and the facts:

  1. If control, security, compliance and resource location are platform requirements, private cloud is your best option.
  2. Comes the responsibility to design, deploy and operate your private cloud — about the exact opposite of a public cloud. There will be hardware, network and storage decisions to be made.
  3. The platform cost is rather steady, although the initial entrance cost will be higher compared to the pay-as-you-go model. So keep your budget tight and do your best to butter up your CFO.

Hybrid cloud (aka the other cloud model)

This happens to be my favorite cloud type by far, even if the exact definition seems to vary based on the vendor, audience and/or the current phase of cloud maturity. Does hybrid cloud mean having a combo of public and private cloud platforms? Or does it mean to utilize physical dedicated servers and cloud resources together? Or simply to leverage a mixture of internal and external cloud resources? In my mind, ‘hybrid cloud’ is the combo of consuming both private (used to provide the steady state resources) and public (used to handle additional traffic spikes) clouds in harmony.

Practical use case for hybrid cloud include:

  • runs resources on private cloud to handle day-to-day activities, then uses public cloud to handle spike traffic activities
  • deploys web tier resources on public cloud, with the application and backend tiers on the private cloud
  • use public cloud resources as a high availability solution to the private cloud published applications.

Why use it and the facts:

  1. It is simply the best of both worlds. You can use both the public and private cloud ecosystems together or independently.
  2. This model demands some sort of cloud strategy and orchestration to keep the consumption of both simple and straightforward. Just as with public cloud, it can turn into the wild wild west if controls are not put in place.
  3. Will require some traffic analysis and crunching of numbers to figure out the right balance between steady state and overflow traffic volumes.
Walter Bentley was a Rackspace Private Cloud Technical Marketing Engineer and author with a diverse background in production systems administration and solutions architecture. He has more than 15 years of experience in sectors such as online marketing, financial, insurance, aviation, the food industry, education and now in technology. In the past, he was typically the requestor, consumer and advisor to companies tin the use of technologies such as OpenStack. Today he’s an OpenStack promoter and cloud educator. Walter helped customers build, design and deploy private clouds built on OpenStack. That includes professional services engagements around operating OpenStack clouds and DevOps engagements creating playbooks/roles with Ansible. He presented and spoke regularly at OpenStack Summits, AnsibleFest and other technology conferences, plus webinars, blog posts and technical reviews. His first book, ‘OpenStack Administration with Ansible’ was released in 2016.


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