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Imagine that all your data is always backed up on a continuous basis and can be rapidly restored to any point you choose. It's not a dream, that's the promise of continuous data protection (CDP), and it may hold the potential to change the backup landscape. At least that's what storage vendors are betting on.
Few vendors agree on what CDP is or whether it is an evolutionary or revolutionary technology. However, all the major storage vendors and a number of startups are getting in on the CDP action with new products and re-branded offerings.
What is CDP?
It depends on who you ask.
There is as of yet no formally approved definition of CDP by a standards body. The Storage Networking Industry Association's (SNIA) Data Management Forum (DMF) is working on a formal definition for a CDP data services interface standard within the Storage Management Initiative Specification (SMI-S).
In the absence of a formal standard, vendors are jockeying for acceptance of their own views of CDP.
Pete Koliopoulos, senior director of product marketing at EMC, told Enterprise Storage Forum that EMC defines CDP as a technology used to minimize lost data and speed the return to service of business applications.
"Specifically, CDP will provide fine-grain, point-in-time views of data and applications for the purposes of data recovery," Koliopoulos said. "We view CDP as an evolutionary not revolutionary technology building on areas in which EMC has unquestioned leadership."
EMC claims that its FullTime RepliStor has been providing CDP-type feature for some time. That said, Koliopoulos noted that EMC is planning a new CDP product in the coming months.
Chris Wood, CTO of Sun Microsystems' data management practice, said Sun's definition of CDP includes a strong availability component.
"The first part is, I want to ensure data is protected as close to instantaneously as I can after creation, and should the primary copy became unavailable, the system needs to automatically and transparently fetch one or more copies of that data," Wood said.
Should Recovery Be Point-in-Time?
From Sun's point of view, the customer must be able to recover data for whatever reason it has become unavailable, and not necessarily on a point-in-time basis, because you never know how far back in time you need to go.
"We need to go back to the last known remaining good copy of the data," Wood said.
Wood said that Sun's StorEdge SAM-FS virtualized multi-tier file system does a form of CDP already called continuous archive.
"We're going to be simplifying and repackaging the message as part of a continuous data message," Wood said. "Right now, we use continuous archive and nobody knows what it means."
That said, Wood said Sun plans significant improvements to SAM-FS, as well as a CDP "box."
Symantec has its own spin on CDP, which it hopes will make the technology more usable and less intimidating to end users.
"We don't abide by the SNIA definition for some specific reasons on the restore side of things," said Brian Greene, Symantec's senior manager of product management. "We found that for the mid-market, exposing every version of every file to the customer and trying to have them decide which one to restore from is overwhelming and intimidating."
Symantec's Backup Exec "Panther" Beta, which will be called Backup Exec Continuous Protection Server when it is officially released in the next several months, prominently features CDP technology
"We protect the files as they change and we capture all those, but we show them the restore view in increments of an hour," Greene said.
Others, however, like Michael Rowan, CTO and co-founder of Revivio, say CDP is all about recovery point objectives and the ability to recover from any point in time.
What Makes CDP Different?
CDP differs from other backup storage technologies in a number of important ways. According to Rowan, all the other technologies that are available, such as snapshots and virtual tape (VTL), are all about storing single point-in-time images.
"CDP is a step away from that in that it's providing continuous recovery points so you can go back to any point in time," Rowan said. "You don't have to think ahead of time about storing an entire image, because using CDP, you can dynamically create any one of those images."
CDP also offers faster recovery and restore than other backup methods, although how much of that is specific to certain vendors is open to debate. Revivio says its own "instant restore" capability offers what it claims are improved recovery time objectives, and Rowan added that CDP technologies in general offers "slightly better" recovery than a snapshot.
A number of vendors say they see CDP as complementary to other continuity options such as virtual tape, although all see recovery point objectives as a differentiator between CDP and other options.
"It's not a company, it's not a product, it is a feature set that needs to be included in data protection," said Michael Parker, manager of product marketing at Symantec. "We don't see it so much as cannibalizing, but rather it will be complementary. Tape is not going away. This is just another offering providing complementary functionality."
Evaluator Group senior analyst Greg Schulz sees the potential for CDP to be more than just another technology layer.
"Short term, I see some initial and point solutions being deployed in conjunction with other solutions and the opportunity for integration services and support," Schulz said.
"Over time," he added, "the big game will involve solutions ... that incorporate some form of CDP or CDP-like data protection technologies. This means more than just simply supporting more snapshots and more flexible RTO and RPO; rather, it means making the overall data protection service delivery experience from configuration to day-to-day operation appear as a seamless function."
"Ultimately, we need to shift from a reactive to a proactive and event-based data protection, something that CDP helps to start to facilitate," Schulz said.
Continuous data protection also goes beyond backup to enable database migration and even real-time fraud detection and auditing, said Info-Tech Research Analyst Curtis Gittens.
"Instead of analyzing logs well after the fact, solutions can analyze database changes on the fly and flag any suspicious behavior," Gittens said. "These solutions can also use CDP to automatically roll back specific types of suspicious data writes."
CDP: The Future
For all the debate over what CDP is, there are few who doubt that it will become a fundamental part of enterprise backup technologies.
"I believe that once CDP becomes adopted mainstream, there is no other way you'll protect your data," predicted Rowan.
"CDP has the potential to become the de-facto standard for data and application recovery," agreed Koliopoulos.
"Today the world is not a batch world," said Sun's Wood. "It's an always availability world, but the backup and restore functionality is still batch. What CDP does is it takes the concept of backup and restore and brings it up to the interactive transactional world that we live in today.
"It's now modeled after the way we're doing business. Is it a huge change in the way we run our shops today? Absolutely, but it's a long time coming and it needs to be here."
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