NASA's Infrared Processing and Analysis Center wasn't shooting for the stars when it turned to virtualization to meet its storage needs. IPAC's cash-strapped effort to record images of our universe -- up to 30 million objects captured each night and 42 billion records over the life of the project -- required big storage capabilities, and the engineers needed them fast and at a low cost.

"We were trying to find a way to step outside of the normal storage purchases to meet our 'high performance and high availability on a budget' requirements," explains Eugean Hacopians, senior systems engineer at IPAC in Pasadena, Calif. IPAC had already purchased a shared-storage system from Seanodes Inc. in Cambridge, Mass., to get control of its clusters with multiple compute nodes.

But Hacopians soon learned that he could put storage on the nodes and that they could work as compute servers and storage servers -- without additional costs or upgrades.

"In general, I'm not really fond of virtualizing things," he says. In his mind, "everything has its own place. But it's a solution that fits a need."

Indeed, virtualization can offer a solution for many storage challenges. But it can also be costly to buy and complex to implement, and it might require you to purchase equipment you didn't need before, such as new switches or servers. How do you decide on the right approach and choose the right vendor? Industry watchers suggest five key questions to ask yourself and your prospective vendors before selecting a storage virtualization technology. (Read a detailed explainer of storage virtualization technology.)

1. What problem are you trying to solve?

The term storage virtualization has become a catchall phrase used to refer to many types of technology that make more efficient use of your storage assets. It can also bring these assets under a single management umbrella with a single point of control.

Since storage virtualization comes in all shapes and sizes, first determine what level of storage you're trying to optimize. Is the pain point at the block level, file level or tape library?

For block-level storage, virtualization can help consolidate large, disparate soft assets in the form of storage tiers, or it can simply bring them all under one roof.

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