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