Like many of the terms used in cloud computing, hybrid cloud has competing definitions because the technology is new and evolving. Cloud consultant Paul Burns defines hybrid cloud as a blend of public and private cloud usage. But cloud engineer Boris Renski believes that it isn’t enough to have private and public cloud in one enterprise to qualify as hybrid cloud. He says that to truly be hybrid there must be “smart interaction” between the two, usually through a cloud application programming interface, or API, that connects them.
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Moving from private to hybrid cloud
At this point, it is safe to say that when vendors or analysts discuss hybrid cloud computing, they could mean either of those two ideas.
Who are the hybrid cloud vendors?
Vendors in general have been more focused on either public or private cloud computing to date, but some have made inroads into the hybrid cloud computing market. Cloud consultant and TechTarget contributor Bill Claybrook cites several as having clear hybrid cloud offerings -- Eucalyptus Systems (partnered with RightScale and compatible with Amazon EC2), VMware, Nimbula (as a management layer over Amazon EC2) and CloudSwitch.
How are public and private clouds connected?
Clouds are connected through APIs in a technical sense and through partnerships in a business sense. Public cloud vendors often partner with private cloud vendors to create hybrid clouds, but as Claybrook points out, cloud interoperability is a problem. There is a proliferation of cloud APIs, but everything doesn’t necessarily fit together. Additionally, all clouds do not run on the same hypervisor, which gives enterprises something to consider when looking at hybrid cloud.
What is cloud
The topic of cloud bursting often comes up in the discussion of hybrid cloud because many see it as the direction hybrid cloud will be taking. A “cloud bursting” application is one that runs on a private cloud but “bursts” into a public cloud during peak times, when it needs more resources. Frequent examples cited are e-commerce companies that need more capacity during the holidays.
Do applications need to be architected differently for the hybrid cloud?
Applications designed to run in a public cloud need to be changed to run in a private cloud if the private cloud is configured differently. In a hybrid model, where an application exists in a private cloud but “bursts” into a public cloud when it needs resources, the private cloud has to be tailored to the application.
Applications need to first be built for the cloud, but then have to be designed with portability in mind so they can operate in different clouds. That is the architectural challenge of hybrid cloud computing.
What applications are best suited to hybrid cloud deployments?
The applications best suited for hybrid cloud computing deployments are ones without predictable workloads. These come in many forms, from a design environment where developers want to test without going through IT to an externally facing app where user demand is high.