Continuous data protection (CDP) fits the bill for unstructured data protection needs

Continuous data protection offers roll back to any point in time, and is a valuable tool in the backup and recovery toolkit, but is it right for your business?

Approximately five years ago, industry buzz said continuous data protection (CDP) was going to be a game-changing technology in data protection. Industry pundits were convinced CDP would replace traditional backup and recovery methods and become the dominant force in the market.

So has the promise lived up to the hype? It's difficult to tell. According to the Gartner research firm, the backup and recovery products market is now worth more than $3 billion globally; however, estimates of the value of the CDP segment have become increasingly difficult as it has moved from being a distinct product category to a subset of backup offerings.

Where market penetration figures do exist -- though these aren't broken down for the UK or EMEA -- they show continuous data protection as a significant presence in some organisations.

Dave Russell, vice president of storage technologies and strategies at Gartner, said that a little less than 18% of large corporations worldwide use some form of CDP in their data centres to safeguard critical applications, while approximately 4% of companies of all sizes employ it (either installed in-house or as a service) to back up sensitive information on client machines.

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CDP deployment considerations

Because CDP snapshots aren't taken at regular timed intervals, it can be difficult to establish when the last backup took place without suitable management tools in place to help.

"When CDP came out, the analogy was that it was like a digital video recorder that would get you to where you wanted to be as if you were fast-forwarding between commercials," Russell said. "But the analogy doesn't hold up. When you record something on video you have visual clues, but that's not true of data, which is all zeros and ones."

This means it's necessary to manually annotate changes such as the installation of a patch or learn to use tools that help automate such documentation. "There have been improvements," Russell said. "But it's not child's play. It requires some level of sophistication to understand what the right recovery point is, so operational and management input is required."

Another disadvantage of real-time backup is that such activity tends to create large numbers of duplicated files, and therefore requires more storage and network capacity. As a result, an infrastructure upgrade may be necessary, which adds to your implementation costs.

Is CDP right for your environment?

Jon Roberts, director of product engineering at colocation provider Interxion, which provides a CDP-based service to clients, said there are limited use cases for which continuous data protection is a good choice.

"You'd be ill-advised to apply CDP to all types of backup because the level of system overhead is quite high," he said. "This can lead to bottlenecks, and the underlying storage requirement can also grow exponentially. There are only a small number of cases where you really need it."

The main consideration in deciding whether CDP is for you is how much data your organisation is prepared to lose from any given system should something go wrong. CDP tends to be used for protecting critical business information or when regulatory requirements demand that no data loss can occur.

Continuous data protection is most suitable with file-based systems rather than in a database application context. Databases use their own form of journaling to ensure data consistency and rollback, which negates any requirement for additional technology.

As a result, CDP tends to be employed in two key scenarios: backing up data centre systems such as Microsoft's SharePoint or Exchange, and protecting desktop and laptop files.

"There are a small number of circumstances where it works really well, but it doesn't fit everything," Roberts said. "So while it was pitched as if it was going to take over the world a few years ago, when we started offering it, we discovered take-up wasn't that great because customers found traditional backup methods worked well enough."

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From point solution to feature: The changing face of CDP

An early inhibitor to CDP uptake was that the technology was poorly integrated with mainstream backup offerings. This didn't go well with enterprises that had invested significant amounts of money in rationalising their data protection systems and were unwilling to invest in point products.

CDP product offerings were initially the preserve of small start-up vendors such as XOsoft and Revivio. The two firms have since been acquired by CA and Symantec, respectively, mirroring the consolidation trend that has seen most tier 1 backup suppliers integrate CDP into their backup products.

At the same time, this consolidation has changed the way continuous data protection has been seen in the market as it increasingly became a subset of wider data protection product suites. "We've taken the stance that CDP isn't going to remain a market, but will become a feature that's embedded in traditional backup and replication solutions," Russell explained. "So rather than CDP taking over from backup, backup is instead absorbing CDP."

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