Cloud interoperability remains wispy, but progress being made

Cloud computing is supposed to make IT more flexible, efficient and easier to manage. But the cloud model threatens to introduce a whole new layer of complexity, unless vendors and industry groups promote interoperability standards that let cloud networks work together.

Vendor competition is a potential impediment, but most major cloud vendors are at least talking about interoperability, including the ability to move workloads from one cloud to another.

"So far, it's closer to lip service, but there are a couple of efforts moving in this direction," says Forrester Research analyst James Staten.

Staten believes the most impressive project is one spearheaded by Distributed Management Task Force (DMTF), which has signed up vendors such as AMD, Cisco, Citrix, EMC, HP, IBM, Intel, Microsoft, Novell, Red Hat, Savvis, Sun Microsystems  and VMware for an effort called the Open Cloud Standards Incubator.

The group will let individual vendors demonstrate interoperability between two clouds and document methodologies to ensure that interoperability, according to Staten. The group thus tackles interoperability on a case-by-case basis, but the hope according to Staten is that this process will spur the development of industry-wide standards over time.

Cloud interoperability can mean many things, and users and vendors may not agree on which types of interoperability are most important. But some commonly discussed goals include the following:

* Moving virtual machines and workloads from one cloud compute service to another.

* Single sign-on for users who access multiple cloud services.

* Ability to deploy and provision resources from multiple cloud services with a single management tool.

* Letting one application span multiple cloud services (such as a storage service from one cloud provider and compute capacity from another).

* Allowing data exchange between clouds.

* Letting a private cloud application seamlessly obtain resources from a public cloud when excess capacity is needed.

In more general terms, enterprises want to avoid using a plethora of cloud services with different interfaces, and don't want to be locked in to a particular cloud by technologies that prevent the movement of workloads from one to another.

Amazon has become perhaps the best-known vendor providing both compute and storage services in the cloud model, and the company's APIs have been called "de facto" standards by those who have expressed hope that Amazon will release them as open source software.

Many companies are supporting the Open Cloud Manifesto, which intends to establish a set of core principles that all cloud providers should follow. But notable absences include Amazon and Microsoft.

Several vendors are attempting to tie together different cloud services in ways that make them easier to use for IT shops, but each effort seems to have some limitation.

VMware, for example, is calling its latest virtualization platform a "cloud operating system" and promising that enterprises can use the software to build private clouds and connect them to public computing resources. But the software only works with hardware that has been virtualized using VMware technology, and the cloud interoperability is only possible if the cloud provider is using VMware. The latter condition eliminates such big players as Amazon and Google.