But worries about availability and being able to back out of your current platform are actually as old as data storage itself.
Adventist Health CTO McGovern remembers working with mainframes 20 years ago, when critical data was backed up to tape. Two copies had to be made of everything, because some tapes turned out to be unreadable, and the nightly backup process would tie up the mainframe for as long as seven hours, he said.
"The Internet storage model is more reliable, more cost-effective and more assured than anything we've done in the past," McGovern said.
Using in-house resources to maintain data gives a feeling of safety and quick availability, but that may be just an illusion, he said. A tape stored in a leaky company warehouse may be less retrievable than data stored in a third-party cloud. Either way, the IT department should go through regular drills to make sure archived data is usable, McGovern said.
Internal storage, one of the most proprietary areas of IT, still has its own costs and pitfalls, said Nucleus Research analyst Rebecca Wettemann.
"If all my data is in a proprietary storage architecture within my own architecture ... is it less difficult to get it out and move it to another vendor? The answer is probably no," Wettemann said. The costs are likely to be higher, too, because a company may have large investments in specialized training as well as hardware and software, she said.
In addition, enterprises are likely to have more leverage with cloud storage providers than with companies that sold them storage infrastructure, Wettemann said. If there's a problem, a service provider will have more incentive to make the customer happy because it needs the next month's subscription fee, she said.
If push really comes to shove, a cloud storage provider might hold a customer's data hostage. At Rackspace, it's never come to that, Engates said. Nirvanix includes language in its contracts that lets it block a customer's access to data, but the company would do everything in its power to resolve a dispute before it came to that, Zierick said.
IDC's Woo thinks serious conflicts between a cloud storage provider and a customer are unlikely because the service is so simple.
"The most optimal relationship to have in a backup scenario ... is a non-existing one," Woo said.