A decade ago, virtual storage was an easily understood concept about using software to administer all your data homes as one big neighborhood, but then at some point it become known as software-defined storage and confusion began to reign.

Lazarus Vekiarides, CTO and cofounder of cloud storage specialist ClearSky Data, likes to point out that software-defined anything–storage, data center, network–isn’t as great as its cheerleaders say.

“I used to be a software-defined storage skeptic. I’m somewhat converted but not really,” he said. “The software-defined storage concept became very cool and ‘in’ when people saw what the hyperscalers were doing.”

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By hyperscalers Vekiarides means the owners of massive cutting-edge data centers such as Amazon, Facebook, and Google, who use their buying power to acquire hardware cheaply. With inexpensive commodity hardware, the thinking goes, you can add independent software to create a storage ecosystem as good as or better than whatever you’d buy from Dell or IBM.

Unfortunately, the math doesn’t work for many companies. “The point that I’ve always made about the hypercalers is: The hyperscalers are not you,” he noted. “Ways that you are not a hyperscaler” would make a good tongue-in-cheek essay for CIOs who think their data is more impressive than it really is, he joked.

Even if the math did work, companies considering software-defined storage need to understand that vendors are selling you the software itself–not the ongoing maintenance. “Operating a lot of this stuff, especially the open-source, is just as difficult as building it,” Vekiarides said. “If you’re an IT guy and your job is just to keep things up, that creates a lot of stuff to learn. You will probably need a lot of expertise that you probably don’t have.”

“I think the answer for most folks is, no, [software-defined storage] is probably not going to work for them because it’s too much trouble. In the end what you’re doing is you’re taking hardware expense and you’re trading it off for people expense,” Vekiarides continued. That might work for a technology company, however. “A lot of interesting storage people are not going to want to work for Widgets ‘R’ Us,” he noted.

“There’s no shortage of people out there who hate their storage vendor, so they’re willing to try anything… just because you could do it doesn’t mean you should do it,” Vekiarides added.

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What to do if you must get software-defined storage

Some companies will make the leap anyway. When shopping, they should demand to see the bill of materials from their hardware vendor, including details as seemingly minor as hard drive firmware revisions and end-of-life advance notices, Vekiarides explained.

On the software side, require the vendor to show you a list of certified servers and independent hardware specifications. The point of all that is so you can build or buy infrastructure on which the virtual storage will definitely work–and you can be covered if it doesn’t work. The risk is that modest hardware changes can void a warranty or cause data corruption.

“If I was a CIO, I would also talk to the bigger system integrators that can actually help you perform this service,” Vekiarides continued. Too few of the companies selling software-defined storage are thinking ahead to future-proof their products against new technologies such as NVMe and persistent memory, except for companies that may want to lock you into their hardware. That trend is already underway, he noted.