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Virtualization vs Private Cloud

Is Virtualization the same with Private Cloud? Are we already running a Private Cloud?

Written on November 21, 2011 by Keng Leong

One of the common question or misconception that I encountered during my customer engagements is that : “I am already running a private cloud because I have virtualized a good proportion of my servers.” or “What is the difference between server virtualization and private cloud?”

To some, the above may sound trivial. But if you try to post this to different experts and gurus, it is likely that you will get different responses and definitions.

I always go back to the definitions of Cloud Computing provided by NIST (NIST Definition of Cloud Computing), because this is currently the most authoritative definition.


  • The Cloud environment that you are building needs to have 5 essential characteristics:
    • On-demand self service : This means there should be some form of self service portal with service catalog that can automatically trigger workflows for routing, approvals and automated provisioning
    • Broad network access : Service is accessible via internet or company network (private cloud) using various devices such as thick/ thin clients, laptops and mobile devices
    • Resource pooling : This implies timesharing of abstracted IT resources (compute, storage, network) from underlying hardware via various enabling technologies such as virtualization
    • Rapid elasticity : This requires one to dynamically increase or decrease IT resources provisioned, according to changing demands, where possible, automatically.
    • Measured service: This means that capacity and utilization is being monitored and reported for capacity planning, demand and forecasting. It also includes monitoring and reporting service usage for the purpose of chargeback or showback.
  • The Cloud service should be implemented using one of the deployment models: Private, Public, Community or Hybrid Cloud models: This drives the enterprise architecture and infrastructure designs, implementation and sourcing strategy.
  • Each Cloud service which you are offering to your users/ customers should eventually fall into one of the 3 service models: IaaS, SaaS or PaaS: The key point here is that you are offering IT as a Service which implies transforming IT to become an IT service provider and sometimes IT service broker (for the case of public and hybrid cloud deployment model) with the necessary service management and governance processes.

Going back to the example of a customer who has virtualized a good number of servers. Is it a running a private cloud?

I would say it has started to build out a private cloud infrastructure, but we need to look at the other things listed above to see where the company is at with its cloud maturity or readiness before we can conclude if it is really running a private cloud. I hope you can see the difference between having a Private Cloud infrastructure and running a Private Cloud - the latter includes how you organize, operate and deliver your IT services from your Private Cloud infrastructure.

Does EMC has a cloud maturity model and where would I be if I have virtualized my servers?

EMC’s cloud maturity model is as shown. If you have virtualized your servers, that may put you at Stage 2 “Abstraction”, assuming that you have not addressed the other aspects.

As mentioned, server virtualization is only the beginning and one of many ways towards cloud computing. Likely, this is also one of the many IT services in your service portfolio. You can also look at offering IaaS, PaaS or SaaS with the other layers such as storage, network, applications and end user computing.