Disk or Tape Backup: How About Both?

Enterprises today have many more backup choices than they used to have, and they're taking advantage by pairing legacy technologies such as tape with newer disk-based data protection options. Depending on budget, performance and availability requirements, enterprises can mix and match different techniques to meet their disaster recovery objectives.

Six years ago, 63% of enterprises relied exclusively on tape backups, according to Dave Russell, research vice president at Gartner. Today, just 13% of enterprises back up directly to tape -- without any disk -- while 65% have adopted a disk-to-disk-to-tape approach, whereby they back up to disk first and then write to tape.

This trend toward a multi-tiered backup infrastructure is expected to remain strong. More than 50% of midsize organizations and more than 75% of large enterprises will implement tiered recovery architectures by 2013, Gartner predicts.

[IN DEPTH: Will cloud backup services finally put tape backups in the trash can?]

Engineering firm Strand Associates has added disk-based backup and recovery tools to its arsenal while moving away from – but not entirely abandoning – tape backups. The combination enables greater backup reliability and much speedier recovery times and has freed the IT team from hours of weekly backup administration tasks.

The Madison, Wisc.-based firm used to do daily tape backups at each of its 11 U.S. offices, where local admins or engineers were responsible for manually performing the backups. There were frequent problems, including failed hardware, lost tapes, accidental overwrites and missed backups, recalls Justin Bell, network engineer at Strand Associates.

Today the firm relies on hourly disk-based snapshots, combined with replication for electronically vaulting offsite data copies and, as a final line of defense, weekly backups to tape.

"The primary driver was looking at the amount of time it would take for us to recover from an incident and how far back we would have to go, how much data we would lose from an incident," Bell says of the decision to upgrade to disk-based backup technologies.

Strand Associates is using FalconStor Software's continuous data protection (CDP) technology. A FalconStor CDP device in each office handles local backup, as well as retains 18 months worth of historical snapshots for that office. "It's replicated all the time, so it's up-to-the-second current with what's on the server. If there were a localized disaster, such as a server dies, we could restore off that pretty easily," Bell says.

Data from each of the remote offices is replicated nightly to a FalconStor CDP device in Wisconsin. In addition, data from headquarters is replicated to a CDP appliance in Illinois, which allows the firm to maintain an offsite copy of its data.

A key benefit of the new system is the ability to recover data from disk very quickly, typically in about 3 to 5 minutes, Bell says. Because it's so easy, the IT team does hundreds of restore jobs each year.

"We view it as a service that we can provide to our users," says Bell, who tells the firm's engineers that "if something happens to a file, or you're designing a roadway and you put some wrong numbers in and you're an hour into it, don't spend a lot of time redoing it. Just call us, and we'll get your file back."

Keeping tape backups in the mix is part of Strand Associates' multitier strategy. "We do the tape to have that last absolute last line of coverage, a last resort," Bell says.

It's an insurance policy of sorts in the event something catastrophic were to happen to the firm's disk-based backup systems. "If you want to erase a year's worth of tapes, it's going to take you a long time to screw up that many tapes. But if you wanted to erase a year's worth of snapshots, it takes about four button clicks," Bell says.

"We haven't had any problems so far, and we haven't had to go back to our tapes since we got FalconStor, but it's nice to know if something happened, if someone accidentally deleted something or screwed up the raid array, that we could go back to tapes if we had to."

On the horizon, there may someday be a place for cloud backup services in Strand Associates' multitier architecture, which would likely further scale back the role of tape. "I think as the cloud proliferates for us, as an additional tier of offsite storage, that will also diminish tape's hold a little bit more," Bell says.

Follow Ann Bednarz on Twitter: twitter.com/annbednarz

Read more about data center in Network World's Data Center section.

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