Hybrid clouds did not get a lot of notice until recently. Many enterprises looking to leverage cloud computing, but not give up any data center space, looked to private clouds as the way to go, but they still wanted to mix in a public cloud or two just for efficiency... okay... coolness. You have to admit, Amazon EC2 looks pretty good on a resume these days.What bothers me about hybrid clouds is that they determine a use case for cloud computing but not really how the architecture should be defined. If you have a private cloud in your data center, typically meaning deep virtualization and multitenancy, and a Salesforce.com account, I'm not sure that really qualifies you to say you have a hybrid cloud, but most are doing so these days.
The value of leveraging hybrid clouds is to have private clouds working together with public clouds, hopefully performing similar types of workloads. Thus, a private cloud that is reaching its saturation point can move some of the processing auto-magically to a public cloud, only using it for the capacity it needs for a limited amount of time.
It's analogous to additional power plants on the grid to provide additional power during peak loads. By leveraging another power plant and just paying for what you use, you don't need to build additional power plants.
The method of moving processing from private to public cloud computing resources is known as "cloud bursting." Cloud bursting could be something that provides the best value around cloud computing if you ask me.
The dirty little secret in the world of cloud computing is that leveraging public clouds is not always cost effective. Many are more expensive than owning your own servers, and once you consider the cost of risk around security, privacy, and compliance, many cloud computing providers are just too pricy.
By leveraging a hybrid cloud configuration the value of public clouds goes way up. Indeed, since you only leverage a public cloud (say Amazon EC2) as you need it for a finite amount of time (say end of month processing), then for a small fee you avoid having many servers and data center square footage that just provide peak processing.
The use of hybrid clouds seems like a pretty compelling use case, but it's not perfect. You have to figure out how processing will move to public clouds, and the mechanisms to make that happen. Interfaces are typically very different, and hybrid architectures are complex distributed architectures, thus initially costly to get up and running. Moreover, even though public clouds provide only part-time processing, you need to consider security, privacy, and compliance issues, as well as management, governance, etc. They are an extension of your architecture, at the end of the day.
The positives and negatives aside, the hybrid architecture could be the killer use case for cloud computing for the next few years. Put this in your IT tool shed for 2011.We have several types of cloud deployments as defined by NIST. They are public, private, community, and hybrid clouds. We all know what private and public clouds are by now, but what about community and hybrid?