In a recent blog post, analyst firm Gartner is questioning if private clouds are becoming obsolete as everything moves over to the public cloud.

“Certainly public cloud IaaS workloads are growing at about six times the rate of on-premises IaaS and for good reasons,” says Alan Waite, Gartner research analyst. “However 80% of workloads are still not on public cloud IaaS, so the short answer is that private workloads are not going away any time soon.

Waite says that despite these figures we will see increasing utilisation of public cloud over the next several years, but there remains a set of workloads that must be isolated and hosted on dedicated infrastructure due to reasons of security, performance, financial models, compatibility, life cycle control or skill sets.

“My observation is that there has been too much emphasis on organisations trying to build their own private cloud IaaS,” Waite says. “This is the most complex and expensive option, and most likely to fail.

He says that what is needed is more nuanced thought about the categories of workloads that need to remain ‘private' and the type of environment in which they should run. “Organisations that try to progress from simple virtualisation straight to private cloud IaaS often fail because of the skills required, the organisational issues and the unexpected complexity,” says Waite. “Many are now considering simpler alternatives to a private cloud IaaS for extending their existing virtualisation environment; either as a first step in a journey to full private cloud IaaS or as a long-term solution when combined with public cloud functions.

In Waite's latest research, Decision Point for Choosing a Private Cloud Implementation Model, the analyst lists five alternatives as the next step after virtualising private workloads: •    Virtual workload management •    Virtual automation •    Private PaaS •    Managed/hosted IaaS private cloud •    Build full-function IaaS private cloud

He says, “Build a private cloud service only after you have developed a complete business case analysis for doing so - it is all about ROI, in terms of cost and business value.”  “You can't outpace public cloud providers in terms of cloud development - pick only what you need for private infrastructure, and implement it well,” Waite explains. “Understand if you are executing a short- or long-term play for those workloads.

“Those applications that are best hosted on public cloud infrastructure should be placed there, and the first option for hosting new workloads and Mode 2 applications should be the public cloud,” says Waite.

“The key to success for your private workloads is to understand the use cases you are addressing with your private cloud initiative, and to do just enough and only as you need it.