Hybrid cloud: it's a term you've likely heard mentioned, but what exactly does it mean and should your firm be investing in it?
In its simplest form, hybrid cloud is a cloud computing infrastructure that incorporates two distinct types of cloud -- usually private and public -- that are linked in a way that allows them to exchange data or applications.
But is it worth your company investing in hybrid cloud infrastructure? There is debate over the question, and some interesting arguments as to why you should perhaps keep investment in private -- and, by extension, hybrid -- cloud to a minimum.
Since hybrid cloud -- under NIST's definition -- will usually involve hooking private clouds to public clouds, the argument hinges around whether companies should really be spending money building out private cloud platforms in the first place.
Private cloud, like public cloud, is used to describe computing infrastructure that users can rapidly provision themselves, that's accessed over a network, that can scale up and down with demand and whose usage can be measured and metered. Unlike public cloud, private cloud is provisioned for the use of a single organisation.
Private and hybrid cloud are sold as offering organisations the best of both worlds: allowing them to control their data and applications when needed, while retaining the flexibility provided by self-provisioning, on-demand cloud infrastructure.
Beyond giving companies oversight of sensitive data, there are a variety of suggested uses for hybrid cloud. These include 'cloud bursting', where a workload initiated in a private cloud offloads tasks to the public cloud when it runs out of local capacity. Another use is to split a system, so that some components run in a private cloud and others in the public cloud -- running the front-end UI on Amazon Web Services (AWS) and back-end elements on a private cloud, for example.
However, according to Laurent Lachal, Ovum's senior analyst for infrastructure solutions, these use cases are largely untested, primarily because hybrid and private cloud deployments are still in their infancy.
"It's very early days. Hybrid is very much a vendor-pushed notion. Very few people have a hybrid strategy because very few have a sophisticated private cloud," he said.
The key question for businesses is, should you be investing in hybrid, and by extension private, cloud?
Probably not, says Lydia Leong, distinguished analyst in the IT Leaders group at Gartner. "In terms of private cloud, the question with private cloud is always 'Why?'," she said.
"What are you doing that both demands agility and flexibility and the ability to self-provision and run programmatic infrastructure? [Where] you need agility and new technology, but not so much new technology that you can deal with the fact that private cloud, technology-wise, is vastly inferior to the features and the capabilities available to public cloud."
According to Leong, the problem for firms considering private cloud is that, as the cost of public cloud drops and the major cloud platforms gain new features, it becomes ever more difficult for a private cloud to match the efficiency and capabilities of public cloud.
"That delta between public and private is only getting greater because of the convergence of the infrastructure-as-a-service space and platform-as-a-service space," said Leong.
"Sure you can get a bunch of virtual machines, but all of the interesting stuff has started to become these solutions that you are getting in the [public] cloud. [Solutions] that accelerate your time to market, that ease management, that drive automation, all these capabilities you're going to miss out on if you do private cloud."
"So, will there be private cloud? Sure, and there are companies for whom it makes sense. If you're Facebook it absolutely makes sense to run a private cloud because you're at such scale, you can get such leverage, you have such a base of technology and a custom highly-tailored use case -- sure it makes sense to do that yourself.
"But for most companies it really doesn't."
Hybrid IT, not hybrid cloud
If the answer for most organisations isn't hybrid cloud then what is it? For those with legacy systems, often it might not be cloud at all -- at least not in the short term.
The answer may well be hybrid IT: that is, running existing, non-cloudy, corporate IT infrastructure alongside public cloud and gradually migrating those systems to the public cloud over time.
"Not everything can or should be cloud," said Gartner's Leong.
"Customers have plenty of applications that they probably will never move to the cloud -- or at least will not move to the cloud in any kind of reasonable timeframe."
"A lot of people still run perfectly fine virtualization infrastructures internally," she added -- a reference to the fact that not all virtualized infrastructure can necessarily be classed as cloud (which by NIST's definition is a platform where users can rapidly provision infrastructure themselves, that is accessed over a network, that can scale up and down with demand and whose usage can be measured and metered).
"Lots of people are still running mainframe systems, for instance, that are unlikely to end up going to the cloud. At least until the applications themselves are replaced."
For those systems where there is no pressing need to move them onto a cloud infrastructure, it can be better to avoid the expense of doing so until necessary, said Leong.
"There isn't necessarily instant ROI on moving to the cloud. Therefore you may want to continue to run things the way that you always run things, for a certain period of time at least, until there is a precipitating event that might require further investment," she explained.
The precipitating event could be technological (a need to replace a decades-old data centre or a scheduled server refresh for example), organisational (a merger or acquisition for example), or a change in business process (introducing a new ERP system for example).
"There are these inflection points that might push you towards moving into the cloud. But otherwise you're fairly likely to move in a hybrid IT fashion for quite some time."
The difference between hybrid IT and hybrid cloud is not just semantic, but has a bearing on cost.
The decision to pursue hybrid IT and keep running a legacy system on existing architecture will likely cost less than building out or buying into a private cloud infrastructure and re-architecting systems to run on that new infrastructure.
The practice of connecting up the old and the new, of colocating enterprise data centres alongside high-speed connections to major public cloud platforms is also growing.
Data centre providers Equinix and Digital Reality make an increasing amount of revenue from hosting enterprise infrastructure in data centres with high-speed connections to the major cloud platforms -- AWS, Microsoft Azure and Google Cloud Platform.
Ovum's Lachal said Equinix generates 17 percent of its revenue from providing this interconnected infrastructure to businesses.
"There's a whole infrastructure being created and an increasing connection between the colocation providers of the world and cloud providers," he said.
For Gartner's Leong, organisations shouldn't start by deciding on the computing infrastructure they will use, but by first settling on what type of IT will best meet the needs of different parts of the business.
Gartner identifies what it refers to as two speeds of IT for business. The first is geared around traditional IT, with an emphasis on efficiency and safety, approval-based governance and price for performance. The second is targeted at agile IT and is focused on supporting prototyping and iterative development, rapid delivery, continuous and process-based governance, and delivering value to the business.
Firms first need to decide which mode of IT will suit which part of the business before settling on which type of infrastructure would best support that mode.
Cloud or non-cloud infrastructure can be used to support either mode of IT, says Leong, although the flexibility and scalability of cloud services mean they are better suited to the agile IT mode.
"There's going to be a certain degree of affinity. Agile things are easier to do in the cloud and therefore you're going to see more mode-two applications in the cloud," she said.
The future of hybrid cloud
Hybrid cloud is not dead in the water, regardless of how few businesses it's a good choice for, says Ovum's Lachal.
"Irrespective of whether it makes sense or not, there are still a lot of investments in private clouds and these are increasingly connected to public cloud services," he said.
More than 40 percent of enterprises surveyed by Ovum in November last year said they were planning to build a hybrid cloud cloud infrastructure or transform an existing one. And according to IDC, by 2018, more than 50 percent of enterprises will create or partner in building and supporting industry cloud platforms.
A few of the companies that sell technology to build private cloud are reporting rising revenues, such as Pivotal with its open-source Platform-as-a-Service (PaaS) offering Cloud Foundry or Red Hat with its OpenShift PaaS.
Businesses engaged in building private and hybrid clouds will often see private as a step towards migrating workloads to public and reducing their own data centre footprint, said Lachal.
"Also, companies aggressively going into public cloud territory are still investing in their own data centres, albeit on a much smaller scale than before."
"GE publicly declared its ambition to migrate something like 60 percent of its apps to AWS, but is still investing in its own data centres. And like GE, many large companies are themselves becoming cloud service providers," he said.
Gartner's Leong argues that there will be a long transition period while businesses continue to undertake hybrid and private cloud projects, as it will take time for mistaken investments in private cloud to become apparent.
"There will still be more people who need to make the private cloud mistake before we're really done with the motion in that market. It's something that people will continue to make mistakes with. As much as we might warn people that 'Hey, this isn't working out well', everyone will still think 'I'm different'."
But Leong says that Gartner has already seen a "tremendous number of private cloud implementations that have functionally failed," where the project "did not end up meeting the business expectations that they wanted out of private cloud".
Another reason why the notion of hybrid and private cloud will persist, she said, is that it's being heavily pushed by the industry.
"Remember you also have a zillion legacy vendors trying to sell customers on the notion of private clouds. All your classic legacy vendors are very hybrid cloud oriented."
Examples of this hybrid cloud focus can be seen in Microsoft's Azure Stack, EMC's $1.2 billion purchase of Virtustream and HPE via its Helion Eucalyptus tools for building AWS-compatible hybrid clouds.
Many of the technologies the major vendors have invested in are designed to migrate workloads from a variety of in-house systems, both private cloud and non-cloud virtualised environments. An example is Oracle's recent purchase of Ravello Systems.
There are also ways of using public cloud that blur the distinction between public and private. Amazon's Virtual Private Cloud allows users to define security and network settings to be in line with in-house infrastructure -- even extending to dedicated host servers and dedicated instances of virtual machines. Microsoft's Azure Stack also promises to bring many of the tools and services from its Azure public cloud to the corporate data centre in a move that could help deliver better parity between public and private cloud.
Potential misstep or not, Ovum's Lachal predicts that organisations will step up investment in hybrid cloud, viewing it as a stepping-stone on a journey towards public cloud and gradually consolidating in-house infrastructure.
"This will take time. Although some companies are very aggressive in their roadmap, the market at large is not quite yet into racing to the public cloud."