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When is a cloud private?

Posted on Tuesday, January 20, 2009 | 3 Comments

When is a cloud private (internal)? I raised this question in a post a few weeks ago.

Maybe we need a better definition for internal Clouds. If you have a single internal data center with a virtualized environment based on VDC-OS what you have is utility computing, not cloud. Once you have two data centers and start choosing to pull services from either one, over your network, you just turned each of them into an internal Cloud, because now they are providing elastic capacity to each other and we have an element of remote delivery of a service, hence matching our definition of Cloud. Once you start to describing, moving and orchestrating these services (workloads) with vCloud, we are truly Cloudy, all be it internally.
I made this distinction based on the agreed definition of 'Cloud'. As pointed out,
Cloud computing is often confused with grid computing, ("a form of distributed computing whereby a 'super and virtual computer' is composed of a cluster of networked, loosely-coupled computers, acting in concert to perform very large tasks"), utility computing (the "packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility such as electricity") and autonomic computing ("computer systems capable of self-management"). Indeed many cloud computing deployments are today powered by grids, have autonomic characteristics and are billed like utilities, but cloud computing can be seen as a natural next step from the grid-utility model. (Wikipedia)
So it was with interest I scanned an article today over at CNet. The argument FOR private clouds. James Urquhart really believes in private (internal) clouds, which is great because I do too! James wanted a quick rebuttal he could use on twitter. Read the article but here is his argument.
Internet has Intranet. Cloud Computing has Private Clouds. Similar disruption, localized scale.
This looks good on the surface, but I think the argument is rubbish.

Private verses external clouds are nothing to do with scale. The difference between Internet and Intranet is about realms of access and security. Internal clouds are about running multiple grid/utility computing instances which are separated by a network, once you have two to choose from, when you move workloads around, then you have internal clouds. Having one grid/utility instance does not make it a cloud. In VMware terms if you are not running the vCloud API you are not cloud.

This is going to be an evolving discussion and I am actually quite keen for someone to beat me into reality here and change my mind. But no one has managed to do that (including people at VMware). If you think you can, post in the comments or find out a way to contact me.

Lets get cloudy!


  1. Anonymous11:57 am

    So maybe James Urquhart had his Twitter argument on track until the final word. I think the Internet v. Intranet comparison makes sense.

  2. I think you missed the context of "scale" in that quote. By "limited scale", I meant that the impact of the disruption caused by a private cloud is limited to that enterprise (and perhaps some supplier/customer integrations). I did not mean to imply that the private clouds themselves couldn't scale to meet any given need, assuming the enterprise owned the necessary equipment.

    Thanks for the thoughtful read, though. Good discussion.

  3. Anonymous5:33 pm

    And lucky James commented otherwise I would have been backing you right up Rod :)


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