Nationwide chose to perform an off-line migration, where host servers are brought down and then reconnected to the new SAN. While it requires a business outage, "it's the least complex, and it's often the fastest," Grantham said.

"We were doing 100 servers in five hours," he said. "Most environments want to be at that stage."

But in order to perform an off-line migration, business unit leaders must be sold on the benefits and reduced risks.

Grantham said a major roadblock to winning approval to any SAN project is gaining business-unit approval, and the way to that is to sell them on the business benefits.

"If you do not sell your business units, consolidation is incredibly hard. I probably went out and met with 60 large-scale business units and said, 'This is what we're doing, this is why, this is your benefit and this is what happens if you don't do it,' " he said.