"A beautiful end state would be a data center with different hardware pieces throughout, all brought together under a software layer so resources can be placed where they are most needed," Forrester's Bartoletti says. But a world of increasing heterogeneity on the hypervisor layer is making that vision more difficult to attain, not easier.
Bringing up the rear
While compute virtualization has become mainstream, network and storage virtualization are less mature, even though the latter has been around for some time. It turns out, this stuff can be pretty difficult to implement.
"The fundamental idea of storage virtualization is similar to that of compute virtualization. Storage no longer has to be dedicated to specific servers or even virtual machines; software instead pools storage resources and makes it possible to centrally manage them. As a result, heterogeneous storage components can be presented as a single resource to virtual machines, obviating the need to manage those disparate storage disks separately. Dru Borden, CEO of cloud storage provider Nirvanix, estimates that less than one-fifth of enterprise customers have true virtualized storage environments deployed - the market is still young."
"When you're talking storage you're talking speeds and feeds," he says, more specifically input and output per second (IOPS). Storage hypervisor vendors that enable resource pooling are reluctant to provide IOPS guarantees when managing competitor's hardware. And if storage virtualization providers can't guarantee performances, IT managers will be reluctant to virtualize storage for their IOPS-heavy tier-1 applications. The promise of storage virtualization is real though: the ability to use commodity storage hardware, instead of proprietary systems from big-name vendors like EMC or NetApp, can yield savings of 30% to 60%, Borden says.
An alternative to on-premises storage virtualization is to use a cloud storage option, which is what Borden's Nirvanix offers. Customers can choose to have storage on their premises on hardware managed by Nirvanix, or in the company's cloud. Virtualized data can migrate between the on-premise hardware and the cloud. EMC, NetApp and other storage giants offer similar services. Borden argues this too is storage virtualization because the data is portable - it uses either internal hardware components or external cloud resources.
But this approach comes with the usual concerns about cloud - perceived security and multi-tenancy risks and questions about bandwidth needs. The possibility to increase value, efficiency and agility are appealing, but implementing storage virtualization in practice is easier said than done, and hence the light market adoption.
Even less mature is network virtualization - the glue that promises to bring together all the elements in the virtual data center.
The fundamental premise of network virtualization is to centralize switching and routing control to make networks easier to manage, more dynamic and easier to scale. Network virtualization "will drastically reduce the provisioning time of network resources, and in an age where IT lives and dies by the time it takes to get things done, that's an advantage," says Martin Casado, VMware's chief networking architect and a pioneer of OpenFlow, a key protocol in the virtual software defined networking (SDN) world.
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