Storage virtualization is becoming more common as companies realise the benefits of consolidating storage-area networks and streamlining their management. As with applications and servers, storage virtualization enables IT departments to de-couple data from dedicated devices. An appliance serves as a go-between from applications and operating systems to the mass storage, enabling you to manage them all using one console. Thirty-eight per cent of IT professionals surveyed recently by CIO said they are piloting or have deployed virtual storage technology, and another 31 per cent are interested in it.

Why you should care?

Virtual storage appliances can extend the life of your legacy storage or help you migrate more easily to new devices through thin provisioning, says Gene Ruth, a senior analyst with Gartner. The virtual appliance automatically maps your data to the usable physical storage space. Though you still have to contend with the physical devices, Ruth says that for day-to-day management, there is a clear benefit to using one console.

Andrew Reichman, a Forrester analyst, says that too often, IT leaders assume the main advantage to virtualization is being able to source storage from multiple vendors; they want to choose the lowest-cost option whenever more capacity is needed, and use the storage appliance to manage the various devices. Vendors have promised this capability, Reichman says, but they haven't yet delivered. "There is a support challenge in having one vendor manage storage arrays from another," he says.

Virtualization still makes it easier to refresh your storage gear, Reichman says, by making the process less disruptive than configuring each new device individually. But beware if you're layering virtual storage on top of legacy systems, notes Ruth: Storage virtualization vendors may only support currently popular disk arrays. Otherwise, follow the same rules you would in any data migration: Wait until off-hours, and make sure you've backed up everything.

What you should do: Reichman notes that adding a virtual storage layer to your network adds to your budget. He advises modeling the costs before taking the plunge, but he says that in an environment in which vendors are compatible, single-console management can provide greater management efficiency.