Amidst all the hype surrounding cloud computing, the hybrid cloud approach-- the blending of both private and public cloud environments--is gaining traction. But the reality of building a bridge that effectively leverages the strengths of both architectures is ending up to be a greater challenge than many anticipated.

With private cloud implementations set to accelerate this year, hybrid clouds, too, are destined to grow in popularity. That means organizations are going to have to ramp up efforts to evaluate application and data location scenarios based on factors such as cost, core business enablement, and business alignment, Unisys said in making its 2012 cloud computing predictions.

Initially, most companies' vision for a hybrid cloud involves offloading some applications to the public cloud, where there is a compelling need to take advantage of scalability benefits, while at the same time maintaining applications that demand a higher level of security in private cloud infrastructures. A longer-term and more sophisticated view of the hybrid cloud blurs the boundaries between public and private environments, creating an infrastructure that allows applications to shuffle seamlessly between them based on need and economics.

Experts say the former hybrid cloud scenario is fairly straightforward and not necessarily new, while the latter instance is where companies are still struggling. "People think it's easy to set up a hybrid cloud, but when you start to mix vendors and technologies, it amps up the level of complexity and the amount of attention required for planning out the solution," noted Dave LeClair, director of product management and marketing for Stratus Technologies, a maker of high availability server and software solutions.

[ Learn more about cloud storage. Read more about what to look for at Cloud Storage Infrastructures Raise Many Issues. ]

Indeed, hybrid cloud models that span an entire environment are a very different animal from a hybrid cloud solution for a single capability, where the application operates on a private platform and so-called "cloud bursts" to a public cloud when transient capability is required, noted Jonathan Shaw, PhD, principal at consulting company Pace Harmon. Another more complex hybrid cloud interpretation is to segregate requirements within a single capability--storage-as-a-service, for example--so that different storage tiers might be delivered privately vs. publicly as part of an overall storage strategy. "This requires virtual machine portability, session management, etc., which is a more complex technical problem," Shaw said.

With an eye towards the more complex hybrid cloud as the end goal, experts say companies need to consider the following factors as part of their deployment roadmap.

1. Understand your IT architecture and application needs.

Not only do companies need to determine what applications and capabilities are suitable for the public cloud vs. a private delivery model (based on factors like demand variability, high availability, response times, and security/privacy requirements), they also need to examine how their applications and workloads are designed to determine if they can be effectively deployed in a hybrid situation.

Typically running some applications on a public cloud and some on a private cloud is a better scenario than spanning a single application across both. "It's much better to have discrete instantiations of applications on one or the other as opposed to a single application spanning both," said Michael Crandell, CEO of RightScale, which provides cloud management capabilities. So for example, you might do R&D work on a private cloud then launch the finished product on a public cloud or vice versa, he explained.

2. Be realistic about the integration challenges that lie ahead.

Crandell said there are at least 10 different public cloud infrastructures, each with their own sets of APIs, not to mention the growing list of private cloud infrastructure offerings like OpenStack or Eucalyptus. The thinking is you can go back and forth and deploy workloads across platforms, but because there is currently no universal standard for workloads in the cloud, you need a portability layer to create the interoperability. "When you start talking about splitting between the public and private cloud environments because you want some level of elasticity, the complexity ramps up dramatically," said Stratus' LeClair. "You need to go into this with both eyes open or you'll find yourself getting into awkward situations where you've moved something that shouldn't have been moved."

3. Factor management tools into the equation.

One of the most critical pieces of a hybrid cloud scenario is a management platform used to monitor and manage the environment with an eye towards resource provisioning, performance, and scalability. The issue here is having a single interface and management layer that can work both sides of the infrastructure. IT shops typically have their own on-premises management consoles for monitoring internal networks while public clouds employ their own set of tools, and a company implementing the hybrid cloud needs visibility into both.

"Unless you want to duplicate work, you have to find a management interface that puts all the resources in a single pane of glass so you don't have to switch between different products to manage this," said Crandell's Rightscale, which offers a product that provides automation, autoscaling, and monitoring capabilities that span public and private clouds.

4. Ramp up organizational skill sets.

Most IT organizations have highly specialized experts who know virtualization, or applications, or servers and backup. A hybrid cloud cuts across all those skill sets and you need to ramp up your team accordingly. "Very few people have the skills that cut across all of these capabilities," said LeClair. "When you're talking about your IT team, there's retraining that has to go on to move beyond how we've run things for the past 25 years."

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