1. A hybrid cloud is a composition of at least one private cloud and at least one public cloud. A hybrid cloud is typically offered in one of two ways: a vendor has a private cloud and forms a partnership with a public cloud provider, or a public cloud provider forms a partnership with a vendor that provides private cloud platforms.
2. A hybrid cloud is a cloud computing environment in which an organisation provides and manages some resources in-house and has others provided externally. For example, an organisation might use a public cloud service, such as Amazon Simple Storage Service (Amazon S3) for archived data but continue to maintain in-house storage for operational customer data. Ideally, the hybrid approach allows a business to take advantage of the scalability and cost-effectiveness that a public cloud computing environment offers without exposing mission-critical applications and data to third-party vulnerabilities. This type of hybrid cloud is also referred to as hybrid IT.
There are a number of types of hybrid implementations evolving.
Hybrid IaaS Infrastructure. This is the implementation of IaaS hardware on the customer premise and MaaS of this infrastructure from the cloud service provider. Example: Intel Hybrid Cloud and HP CloudSystem.
Hybrid IaaS Services. This is integrating a public cloud service (like backup) with your existing systems or your private cloud systems.
Hybrid SaaS. This is simply combining public services with your existing sytems to create new applications and business processes. For example, using your salesforce.com data, a public web service like mapping and your internal customer billing information to create a mash-up application mapping your customer sales, customer satisfaction or other information for trending and analysis.
maintain investment in existing systems
applications or sensitive data can remain in your private network
less management than a private cloud
greater control of your systems incluing architecture, access, data location, user experience, etc., but not full control as in a private cloud
more efficient and potentially lower cost than your existing systems and less cost than building your own private cloud or data centre.
Increased complexity (over public cloud)
Increased management requirements (over public cloud)
Increased costs (over public cloud)