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How do public, private clouds stack up to tape backups?

Private clouds represent another threat to tape backups, but there are cost and data retention concerns that enable tape to remain a viable option.

The public cloud has been an alternative to using off-site tape for backups for several years, especially for smaller companies. But what about the private cloud? It is also emerging as a backup option as larger organizations build their own clouds.

A good example is Canadian consulting engineering firm exp, which ditched its tape and virtual tape libraries and built a private backup cloud with Panzura Cloud Storage Controllers and EMC Atmos to protect data in remote sites.

"As a concept, using the cloud -- whether public or private -- as a large component of your backup regimen is definitely an emerging trend," said Rachel Dines of Cambridge, Mass.-based Forrester Research Inc. "I'm seeing quite a bit of adoption of disk-to-disk-to-cloud. That's essentially what exp did here; backing up to a local appliance and then replicating it to a cloud infrastructure and then also replicating it on the back end for disaster recovery or other uses."

Dines said using the cloud is a sound alternative to relying on tape, which has long recovery times.

"Data centers are tapped out," she said. "They don't have the capacity to keep all [the] backups they want for capacity and cooling reasons. Keep it a day or two on-site and keep the rest in the cloud, which frees up a lot of capacity in the data center."

Another analyst said it is a bad idea to eliminate tape and move entirely to the cloud.

"I hate it," said Ben Woo, managing director of New York City-based Neuralytix Inc. "I think there's still an absolute need and an absolute place for tape, particularly for large organizations."

Woo said he considers tape especially useful for disaster recovery.

"Cloud is great for fault tolerance, but when it comes to true disaster recovery, when there are unfortunately man-made or natural disasters like 9-11 or Sandy, [and] you need to rebuild your data center from scratch, to me, there's no alternative to tape," he said. "What are you going to do with the cloud? You're not going to pull the wires over the Internet. Some may upload that data to some form of disk, but ultimately, there's still a physical transaction that needs to take place [to get] the data back and [go] through it. I'm just not one of these people sold on getting rid of tape; period."

When it comes to comparing tape and the cloud on cost, Woo said, "Tape will always be the cheapest medium on which you can store information. Nobody has shown me documentation anywhere that says cloud backup is going to be cheaper than tape overall."

Dines said the cost issue revolves around how long you're keeping the data and the likelihood of needing to restore it.

"If it's data kept for a short period of time and something you're unlikely to need to have to pull back, cloud can be a very attractive option, pricewise," she said. "But if it's something you're keeping for many years, the equation flips back to tape being less expensive. That's why I'm not seeing many organizations take a monolithic approach."

At this stage, it looks like disk, tape, public clouds and private clouds are all viable options depending on a company's needs. Connor Fee, director of marketing for Natick, Mass.-based cloud-integrated storage vendor Nasuni, said the public cloud is usually the better option for storage than private clouds. Nasuni, which moves data off to clouds similarly to Panzura, has published results of its performance testing with cloud providers.

"Public is better than private -- with one caveat," Fee said. "When I say public cloud vs. private cloud, I am referring exclusively to storage. I can say that because we've run four years of annual testing and I can tell you that the best of the public stuff is so much better than the rest of the public stuff, and definitely better than what you're running with private stuff. The other caveat is the customer owns, holds and applies a private encryption key. If you're going to use a public cloud, you have to own and control the encryption. Most solutions do that now, but it's a glaring hole if you don't have that."

Woo said the debate between private vs. public cloud is "really a conversation about liability and responsibility. Public cloud means you want to shift some responsibility to somebody else to manage. Some argue there is a shift of legal liability. I don't buy that because at the end of the day, you have to walk up to the CEO and say, 'We lost data.' You won't get a chance to say, 'but it wasn't my fault.' You can get fired after 'we lost data.' There's also a sensitivity to a third party touching the data. Some folks believe, 'There's absolutely no way in the world our data leaves our data center.'"

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