I find myself confusing to understand the concept of private cloud. If a company has an offshore data-center, and now if the company wants to move into a private cloud, what does the company has to do?

If I am correct, in order to use the term cloud, there should be virtualization. If there is no virtualization, there is no cloud. So is a private cloud, where you virtualize your existing data center? Or is it simply throwing out your existing hardware and purchasing hardware from a cloud provider, so that now all your resources are on the Internet?

And also how does the private cloud differ from virtual private cloud?

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    Cloud is a pretty generic term. You could build your own and call it a cloud whether you keep it private to you or your company or not. – JeffO Oct 3 '14 at 11:40

"Cloud" is simply a trendy term for "on someone else's computer". (That, by the way, is also a great handy way of deciding whether or not it's a good idea to move something to the cloud or not.) If you run processes on computers owned by someone else who has a data center specifically for providing this service, that's the cloud. Virtualization is not strictly necessary, but usually done because it's a better deal for the cloud provider.

A private cloud is the same except that your company also owns the data center (or maybe owns the company that owns the data center). Theoretically, if you're a customer of Amazon's cloud services, and one day you get really, really rich and buy Amazon wholesale, you've moved from cloud usage to private cloud usage without anything else changing.

  • can I rent some fixed number of physical servers from Amazon and call it as my private cloud? – DesirePRG Oct 3 '14 at 17:02
  • Cloud is more than that, though. The idea centers around virtualization, meaning you can add more CPU, memory, disk space, whatever resources you need to get your job done and you pay for what you use. Maybe those extra CPUs are on the same physical server, maybe not: my understanding is a cloud provider uses clusters of microcomputers to build a large server, which is then divvied up into slices based on customer demand. – user22815 Oct 4 '14 at 0:13
  • "As an aside, it should be noted that an increasing number of IT companies are also starting to use the term "private cloud" to refer to the building of a cloud computing infrastrucuture -- or "internal cloud" -- within a company's own data centre. Such a development is not really cloud computing at all, and may be regarded as a last-ditch attempt to maintain the status quo. Under any sensible definition, a "private cloud" has to be a cloud computing arrangement where the hardware concerned is owned and housed in a vendor's shared data centre" source:explainingcomputers.com/cloud.html – DesirePRG Oct 8 '14 at 9:59
  • Your answer is contradicting with the above source. – DesirePRG Oct 8 '14 at 10:00
  • @Kilian Those definitions are inaccurate per NIST nvlpubs.nist.gov/nistpubs/Legacy/SP/…: "Cloud computing is a model for...ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources...that can be rapidly provisioned and released w/ minimal management effort..." and defines private cloud as "The cloud infrastructure is provisioned for exclusive use by a single organization...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." – Matthew Sep 21 '16 at 0:19

My understanding is that a "Private Cloud" is a cloud which is used solely by one organization. It does not matter if it is a third party or a hosted service.

The opposite is a "public cloud" which means that the cloud services are open for public use.

Now, regarding "virtual private cloud". This is using virtualization services to create a private cloud. For example, you have a single server which virtualizes 3 servers (an FTP server, a Web server and a DB Server). They all belong to the same "Virtual Cloud" and they are private because they are solely used by your company.

Anyway, Cloud is a buzzword nowadays. My understanding is that it always involve virtualization, be it in an infrastructure, platform or service level. This is what creates the other terms IaaS, PaaS and SaaS.

For reference you can check: http://en.wikipedia.org/wiki/Cloud_computing also maybe the presentations from https://courses.edx.org/courses/BerkeleyX/CS-169.1x/2013_Summer/info

I hope this helps.


The answer is, if it's your private cloud, then whoever you choose.

Cloud means something like "software and/or data accessible through the Internet and not necessarily situated at any fixed location." The location might be "Singapore" but not "that slice in that rack in that bay of that data centre".

Private cloud means that you largely own and control the software and the data, but not the hardware. You decide what version of the software to run, how the data is organised and stored, and who gets access to the software and data. Obviously there are degrees of this, but you have the ultimate control of your private cloud, but not the hardware it runs on or exactly where it is located.

Virtualisation is not important, except as a possible implementation mechanism.


Cloud refers to servers that are accessed over the Internet, and the software and databases that run on those servers. Cloud servers are located in data centers all over the world. By using cloud computing, users and companies don't have to manage physical servers themselves or run software applications on their own machines

Private clouds are cloud environments solely dedicated to the end user, usually within the user’s firewall. Although private clouds traditionally ran on-premise, organizations are now building private clouds on rented, vendor-owned data centers located off-premise.

All clouds become private clouds when the underlying IT infrastructure is dedicated to a single customer with completely isolated access.

A private cloud uses virtualization technology to combine resources sourced from physical hardware into shared pools. This way, the cloud doesn't have to create environments by virtualizing resources one at a time from a bunch of different physical systems.

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