Continuous data protection backup tutorial on CDP tools

In this continuous data protection backup tutorial, learn about how CDP tools are being used, what you need in a CDP tool, and near-CDP vs. real-CDP.

By Dave Raffo, Senior News Director

Over the last two years, continuous data protection (CDP) has made its way off the overhyped technology list and is rapidly picking up steam as a useful piece of the data backup and recovery puzzle.

The Storage Networking Industry Association (SNIA) defines CDP as "a class of mechanisms that continuously capture or track data modifications enabling recovery to previous points in time." In this tutorial on continuous data protection backup, learn about the latest CDP tools, how CDP is being used today, and about the latest CDP products.


An introduction to continuous data protection in backup
A history of CDP tools 
How CDP products are being used today 
Near-CDP vs. real-CDP 



CDP tools first surfaced around 2005, promising to lower recovery point objectives (RPOs) and ensure data restores. However, CDP attracted few customers and most of the companies offering CDP either were acquired or went out of business.

TechTarget Executive editor and independent backup expert W. Curtis Preston lists three reasons why CDP initially failed: Most of the early CDP vendors were startups; it was positioned as a replacement for traditional backup; and products were immature. Technology failings included a lack of application-awareness and the inability to handle both on-site and off-site copies of data.

The CDP landscape has changed over the past few years, however. Today's CDP products include EMC Corp.'s RecoverPoint, Symantec Corp. NetBackup RealTime, and IBM Corp. Tivoli Storage Manager FastBack. Most of the smaller backup vendors also have CDP.

CDP technology has also improved -- a single CDP product can give you on-site and off-site protection, and products can be integrated with popular applications such as Oracle and Microsoft Exchange and SQL Server.

With servers growing in size, server virtualization taking off, and recovery time objectives (RTOS) and RPOs shrinking, organizations have more reason to desire instant recovery for mission-critical data. When used with synchronous replication between a client and a backup server, CDP can provide a zero second RPO and recover a server in seconds.


Editor's Tip: Listen to this podcast with W. Curtis Preston about how continuous data protection backup could eventually replace traditional data backup and recovery.


CDP tools were first sold by startups trying to take on established backup vendors. The original CDP startups didn't make it, although some of their products and IP did. For instance, EMC bought Kashya for replication and was pleasantly surprised at its CDP capabilities; CA Inc. acquired XOsoft and turned its CDP into ARCserve High Availability; IBM picked up FilesX to add CDP to Tivoli Storage Manager (TSM); and Symantec acquired Revivio's CDP assets to enhance its backup software.

Through all these changes, the underlying goal of CDP has remained the same: to give customers a way to recover data to a previous point in time -- ideally to support an RPO of close to zero seconds.

Nearly every data protection vendor has a CDP tool on the market today. Dedicated CDP tools include AppAssure Software Inc. Replay 4, Atempo Inc. Live Backup, CA ARCserve Replication and High Availability, Cofio Software Inc. AIMstor CDP, EMC RecoverPoint, FalconStor Software Inc. FalconStor Continuous Data Protector, IBM Tivoli Storage Manager FastBack, InMage DR-Scout, Symantec NetBackup RealTime, and Vision Solutions Inc. Double-Take Backup.


Editor's Tip: For more information on CDP tools, listen to this podcast about how CDP is being integrated into more and more backup and recovery tools.


According to an April Enterprise Strategy Group (ESG) survey of 510 senior IT professionals, CDP use has increased 18% since 2008 and another 43% of respondents plan to implement CDP products over the next two years. That makes CDP almost as popular as data deduplication -- a technology that gets far more attention. The ESG survey found 38% of respondents use dedupe and another 40% plan to implement dedupe over the next two years.

The most recent SearchStorage/Storage magazine Purchasing Intentions survey doesn't indicate the same amount of use, but shows adoption rates have soared, and interest in CDP is at a high point. Over the last four years, usage has risen from 5% to 13%. Sixty percent said they plan to increase CDP spending or keep it the same as last year -- the highest total ever in the survey.

The interest in CDP among organizations with larger quantities of data to back up and recover can likely be attributed to issues with meeting backup windows.


Enterprise Strategy Group report,

Organizations using CDP tend to have larger data stores to protect. According to the ESG report, 42% of respondents with more than 100 TB of data currently use CDP and another 42% plan to adopt it within two years. That compares to 26% of those with fewer than 100 TB using CDP, and 47% planning to deploy the technology.

"The interest in CDP among organizations with larger quantities of data to back up and recover can likely be attributed to issues with meeting backup windows," according to the ESG report, written by analysts Lauren Whitehouse and Bill Lundell. "Since CDP provides continuous backup, there is no need to allot specific times that backup processes can run so as to mitigate impact on production server performance. Organizations with large volumes of data and limited backup windows would have greater interest in eliminating the need for that backup window and, more importantly, guaranteeing successful completion of backup processes."

The ESG survey found 14% of those implementing CDP use it to replace traditional backup, with 18% combining CDP and snapshots to replace traditional backup.

That means CDP is used mostly to complement the traditional backup process, and often combined with replication to enable high availability and disaster recovery. EMC said CDP licenses tripled within three years of its acquiring Kashya and selling its RecoverPoint replication/CDP product for operational recovery. CDP products from vendors such as CA, Neverfail and Vision Solutions/Double-Take are commonly used for high availability of critical applications such as Oracle and Microsoft Windows and Exchange 2010.

The rapid rise of virtual servers is also driving CDP use -- especially as virtual machines are adopted for production data -- because CDP can recover all virtual machines in an environment instantaneously without data loss. The recent SearchStorage/Storage magazine purchasing survey found use of CDP to back up virtual machines went from under 2% to 6% in the past year.


Editor's Tip: For more information, learn about how you can simplify virtual machine backup with CDP and near-CDP.


When CDP pioneers objected to snapshot-based products such as Microsoft Data Protection Manager that claimed to do CDP, the near-CDP category was born to differentiate between the two. Any backup product that takes snapshots and replicates does near-CDP. Like CDP, near-CDP technology also provides instantaneous recovery, allowing your application to immediately mount a recovery image when the primary image is damaged. The difference between the two is the RPO that they offer. CDP offers an RPO of zero, and near-CDP offers an RPO of however often you are taking a snapshot (typically one hour).

CDP isn't the hottest disk backup technology anymore, and probably will never reach the hype it generated in 2005 to 2006. But with a valuable role in disaster recovery as a complement to replication and a growing user base, the technology isn't going away any time soon.


Editor's Tip: Learn the differences between near-CDP vs. real-CDP in this article.


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