Fuentes uses storage systems from HP, NetApp and EMC in an environment that handles multiple petabytes of data.

With one vendor, "they know what you need and they can set the tone for the conversation," said Fuentes. "If you have multiple vendors, you set the tone."

It takes more work to support different hardware devices, said Fuentes, but the tradeoff is still worth it.

"It's not the amount of the work you have to put in it," said Fuentes, about supporting multiple system, "but what's best for your business."

Similarly, Jim Sievers, a systems infrastructure manager at a user firm, buys x86 servers from three vendors, HP, Dell and Cisco.