Even though the are many concerns in using Public Cloud, large enterprises are adopting Cloud delivery model aggressively. If Gartner’s predictions are correct, Cloud services will be a $148 billion market by 2014. By then industry would have some standards which will alleviate concerns like vendor lock-in and also solutions for security related concerns. But to understand what enterprises are doing in order to overcome the current concerns about Public Cloud we need to look at the Cloud deployment models

There are three basic deployment models. There can be variants but can be mapped back to one of these three deployment models.

Public Cloud: Cloud services owned by an organization and made available to the general public to use fall under this deployment model. Amazon’s AWS and Google Apps are some of the examples which are available for the general public to use and billed only for the time it is used. The services will be on a shared infrastructure where muti-tenants can be serviced from which provides a huge cost advantage.

Private Cloud: Cloud services which are operated solely for an organization is defined as Private Cloud. The services can be managed by the organization itself or by another organization and also it can be on premise or off premise. This model will not provide the same cost benefit as the Public Cloud but is a balance to the concerns most enterprises currently have moving to a public Cloud.

Hybrid Cloud: Cloud services which utilizes a combination of Public and Private Cloud fall under this category. One scenario can be an enterprise with its own Private Cloud utilizing a Cloud Storage vendor service to archive its non critical data. This requires following a standard for the interface between the Cloud implementations and a good governance model.

NIST defines another Cloud deployment model called “Community Cloud” but can be mapped back as a variant of Public Cloud which is accessible only to a group of organizations.

To mitigate the concerns of using the Public Cloud large enterprises having their own data centers are moving to Private Cloud model. Even though they don’t get the same cost benefit as using the Public Cloud, the consolidation and abstraction of the infrastructure done as part of the Cloud implementation makes their IT infrastructure more dynamic and nimble.