Continuous data protection does not mean ‘snapshot’

A spate of corporate acquisitions and product launches have made more IT managers aware of continuous data protection (CDP), but vendors and analysts say many don’t understand the difference between CDP and snapshots.

“People use the term (CDP) very loosely,” said Diane Clay, director of marketing for Rivivio Inc., a Lexington, Mass.-based storage vendor. Clay described CDP – which is designed to provide byte- or block-level backups of every change made to an application or database – as different from snapshots, which back up files at intervals chosen by administrators.

“That’s not saying (snapshots) are not valuable, but they’re not truly continuous,” she said, adding CDP allows “instant recovery” while snapshots require more storage space.

“You can always guarantee that the snapshot will come at the worst possible time,” she said. “That’s just Murphy’s Law.”

She claims administrators can recover applications with Revivio’s CPS 1200 appliance in 10 to 15 seconds with a few mouse clicks, and CDP only adds 10 to 15 per cent to an application’s storage requirements.

But taking four different snapshots of a 5TB database will required 20TB of storage space and could take an hour to recover, she said.

The shorter recovery time and the ability to recover more recent data are two of the major benefits of CDP, said Natalya Yezhkova, research manager of the storage systems group at market research firm IDC of Framingham, Mass.

In a recent IDC survey of chief information officers, IS managers and other IT professionals, 61 per cent of respondents said they had a “good understanding” of CDP, compared with 25 per cent in a similar survey last year.

Rhoda Phillips, research manager of IDC’s storage software group, said recent corporate acquisitions have raised awareness of CDP. For example, in May, EMC Corp. of Hopkinton, Mass. bought Israeli networked storage vendor Kashya Inc., and in July, CA Inc. of Islandia, N.Y. bought Xosoft. Yezhkova said only six per cent of respondents this year said they had never heard of CDP, compared to 22 per cent last year.

But when IDC asked respondents who said they understood CDP to define it, the answers “indicate people have a limited understanding of what it is,” Yezhkova said.

IDC advises users to investigate the return on investment before making a purchase decision, but some vendors describe the technology as an “insurance policy,” where it is difficult to calculate a return.

One corrupt piece of data can be extremely costly, said Gil Rapaport, Xosoft‘s vice-president of marketing and product management.

“It’s almost impossible to make an accurate ROI,” Rapaport said. “Let’s say you lost five e-mails, and one was from an important customer and you need to receive this e-mail.”

In some industries, such as financial services, a minute of downtime can cost thousands of dollars, said Rick Walsworth, marketing director for EMC’s infrastructure software group.

Companies without CDP may back up data to tape, which will still allow disaster recovery, Walsworth said.

“12 hours later, they’re back in business, but back in business with yesterday’s data.”

Comment: info@itbusiness.ca

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