Storage is the Achilles heel of virtualization projects, said Lefthand Networks as it announced a new version of its iSCSI SAN software, which it claimed could ease the task of rolling out virtual desktop infrastructures (VDI).

The company said that the Linux-based software, called SAN/iQ version 8, runs on an x86 server - or preferably a pair of them, for redundancy - and uses storage virtualization technology to turn a bunch of disk arrays into a powerful but relatively cheap SAN-in-a-box.

It said that new features in version 8 - including SmartClone volumes, an integrated performance manager, a virtual connection manager, and APIs for links to other management consoles - would make it easier to manage virtualized environments and cut storage costs.

Virtualization may reduce the number of physical systems needed and simplify some aspects of administration, but it increases the complexity of the logical infrastructure and it creates bottlenecks in new places, argued Larry Cormier, LeftHand's marketing VP.

"For example, VDI changes the whole capacity/performance picture - you need more spindles for performance, for when all your users log in," he said. "It's also hard to manage performance on virtual servers, and today's environment multiplies the number of logical connections coming out of each box, and it's hard to visualize those."

A virtualized SAN provides those spindles more efficiently than NAS systems could, and is also more flexible, he claimed.

He added that the SmartClone feature resembles a snapshot, in that it's a virtual copy of a volume that you can carry on using and adding to. It also combines thin provisioning and de-duplication, because the clone volume stores only the changes and simply refers back to the source volume for the rest.

For example, you could set up a standard image for a virtual server or desktop and then clone that. The VMs would share the same base image, which economizes on storage as the only physical space they take up on disk is their working area.

Cormier acknowledged that there's already similar technology for file-based storage, such as NetApp's FlexClone, but said this is the first time it's been built into block-based storage. "It's a way of using thin provisioning and de-duplication to combat VM sprawl," he adds.