What is the difference between private cloud and public cloud?

Question

What are the differences between private cloud and public cloud ?

Please define both and giving examples with usage.

Unreadable

Not really a question for Stack Overflow. – Arnitaarno

I'm fine with most noob questions, but the difference between public and private can be found in any english dictionary. – Tiffa

@Tiffa it's not a simple difference of one-word vocabulary. It's actually a much more complicated question, that few of the answers actually touch upon the difference of – Kiwi

@NicoHuysamen out of curiosity, do you think this is better for SuperUser? or which other SEx sites? – Kiwi

@FlakDiNenno - Mmm, yeah maybe SuperUser rather. Or maybe Webmasters or WebApplications, maybe even Computer Science, but definitely not StackOverflow. – Arnitaarno

@NicoHuysamen but, the more I think about it... the more I think that it might be... b/c you might need to consider things like security, SSO, even calling 3rd party APIs, which these days are built into / available as services or marketplace offerings in public clouds that you wouldn't have access to in a private one. These are important things to consider in deciding what to build into / handle more natively in your app and what to rely on your environment and decoupled services to handle for you. – Kiwi

@FlakDiNenno - Sure, but that is not the question asked. As the question is stated, there is no programming relevance; rather something like a textbook answer required in a under-graduate exam. – Arnitaarno

@NicoHuysamen ok, I see what you're saying. although, I don't think that's the right analogy... as it's not so much about a wrote definition / answer... but, the fact that as written the question has not specific programming relevance ;-) – Kiwi

@FlakDiNenno - Bingo-bingo <insert finger guns> – Arnitaarno

@sany I think the community wiki answer should be considered as your accepted answer. – Papageno

Answer 1

A public cloud is offered as a service via web applications/web services( usually over an Internet connection). Private cloud and internal cloud are deployed inside the firewall and managed by the user organization.

There is another type of cloud, hybrid cloud. A hybrid cloud environment consisting of multiple internal and/or external providers will be typical for most enterprises.

You will get more understanding here.

Morn

Answer 2

The same as the difference between an intranet and the internet. A private cloud is one set up for a specific group or organisation and usually isolated from the big bad world (behind firewalls and such).

A public cloud is, well, public, out on the internet proper.

For example, a certain big company I know does cloud computing but only using servers they control. It gives them the same benefits as public cloud computing but with more control and less security worries.

They also do public cloud computing but they wouldn't be comfortable to allow control or access to their more precious data to be at the whim of anyone else.

Ischium

Answer 3

The answers above were fine for 2010, however standards have since emerged and NIST has come out with actual definitions of public and private clouds (see NIST Cloud Computing Definitions) NIST definitions are belowm, the italics are mine:

• Private cloud. The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units). It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off premises. A private cloud may be provisioned any way an organization may like, with internal networks or a DMZ with some machines available to the public. Private clouds can resolve the noisy neighbor issues of public clouds - however depending on how the infrastructure is set up, you might end up becoming your own noisy neighbor.

• Public cloud. The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the cloud provider. Quite possibly this is what everyone thinks of when they hear of Cloud, and make it almost synonymous with Amazon, although they are only 1 of the ever growing list of public cloud providers.

• Community cloud. The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises. These are probably the next boom in clouds, but suffer a marketing problem. Recently I've seen them marketed as private clouds, but they share certain benefits, eg. HIPPA compliant clouds can be provisioned in a HIPPA compliant data center.

• Hybrid cloud. The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds)

Lifeline

Answer 4

If you are talking about the IaaS ? (Infrastructure as a Service )

Public Cloud : Example : AWS,RackSpace,SkyTap and Many more All of these provides computation,storage,networking as a Infrastructure with varied options and use cases, served for public with a standard fee. Somebody else home for Infrastructure, you rent it based on your need.

Private Cloud : Hardware Servers, Racks, Hypervisors,Router,Core Switch and Cloud Management Software. All of the above provides you to manage the computation,storage,networking the way best fits to your need. Its all Private Its only you have built this Private Cloud for your own needs. Your own home the way you want, No rental.

Prandial

Answer 5

Adding to the discussion, Public Clouds are built by organization for selling the computation as as service to the public where as Private Clouds are built for computation purposes of the organization itself(for their own need)

For example, Amazon EC2 or Rackspace DataCenters can be catagorized into Public Cloud systems and Google or Facebook DataCenters can be catagorized into Private Clouds, the difference being the purpose for which they are built

Mephitis

Oops, sorry Just realized that I bumped into an old thread :D – Mephitis

Answer 6

It all comes down to who has responsibility for the equipment.

In the public cloud, the organization has no local hardware to manage or maintain. All the resources and services run on the cloud computing provider's hardware.

A private cloud is an organization's on-premise datacenter that runs cloud management software. This cloud management software can make your on-premise datacenter like the public cloud but it's only for your organization. The cloud management software apply virtualization to all your physical hardware and you can enable access to these virtual machines by internet

Vagal