Bret Piatt

How to tell the difference between “cloud” and “virtualization”

by Bret Piatt on Feb.07, 2010, under Technology

Many people seem to think “cloud” is just off-premise “virtualization”.  Cloud comes in a few flavors and I’ll argue that you can have “private cloud” either hosted off-premise in a provider’s facility or in your own.  The fundamental difference between cloud and virtualization is the goal of cloud is to automate provisioning (this applies to IaaS, PaaS, and SaaS) and the goal of virtualization is resource utilization optimization.  You can (and many providers do) use virtualization as the basis for building a cloud but it is not required.

If we take a look at the Reductive Labs presentation from OpsCamp slide 3 illustrates the primary benefit of cloud.  Cloud helps companies even if their minimum unit of work is larger than a single host machine where virtualization just adds overhead in that case.  The difference between “cloud” and “grid computing” or HPC is that grid/HPC process jobs in a batch manner rather than serve interactive applications.  You can build a compute grid on top of a cloud but not vice versa.

Other folks are saying “private clouds can’t exist because you can’t have rapid elasticity and pay for what you use”.  For a small company you may not be able to have a private cloud but for a large enterprise with many business units you certainly can.  An IT infrastructure BU can provide other organizations in the company all of the requirements of a cloud.

For public cloud to succeed they need to provide all three

Depending on the current utilization across an enterprises infrastructure they may be able to defer spending for a number of years by moving to a fully cloud enabled business.  Right now many departments cling to servers they don’t need because they’re afraid if they release it they’ll never get it back.  With cloud removing that fear resource hoarding ends and many enterprises will have a significant increase in available computing power.

Over the long term if the public computing clouds continue to grow, increase their transparency, and optimize their delivery models it will no longer make financial sense for enterprises to build their own infrastructure.  Public cloud providers will need to prove over the next decade they can deliver on all three corners of the “impossible triangle”.

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  • [...]This article was reposted on http://www.privatecloud.com/2-22-10/[...]
  • Rick Parker
    Totally incorrect that vitualization is not required. Cloud is not just to automate provisioning but to provide rapid provisioning that can not be done without vitualization. The proof is that cloud computing did not exist prior to virtualization.
  • I'll reference the NIST definition on cloud computing:

    On-demand self-service.
    Broad network access.
    Resource pooling.
    Rapid elasticity.
    Measured Service.

    Virtualization is not required to meet any of those, you can rapidly provision physical nodes in a number of ways. Most clouds copy images across the network to the VM host machine when you launch a new image, there is no difference to copy over an OS that runs without virtualization. It is also possible to PXE boot and have a diskless host machine without virtualization if you want more rapid boot times.

    Cloud computing did exist prior to virtualization, we just didn't call it "cloud" and most people didn't use it because of the price of resources -- many enterprises have been running multi-tenant application grids for a decade or more that meet the definition above.

    Now thanks to globally ubiquitous network access public cloud computing is interesting as well. Combine that with Moore's law and its ability to continually decrease the price per compute unit and on demand computing and data analysis job processing is interesting to more and more folks.
  • Rick Parker
    A partial section of the NIST definition is below, see rapid provisioning. No you cant rapidly provision physical servers as quickly as virtual. multi tenant doe not equal cloud and cloud also equals less expensive which directly contradicts multi tenant equals cloud

    Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. This cloud model promotes availability and is composed of five essential characteristics, three service models, and four deployment models.
  • Brenna
    There is also another option of having an "enterprise hybrid cloud" that is managed, flexible and scalable - blending dedicated and cloud resources in a single solution.I think that is the solution to delivering the "impossible triangle". Companies are already partnering to approach this like Carpathia/Citrix -> http://carpathiahosting.com/enterprisecloud
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