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How continuous data protection is used today

When CDP emerged a few years ago, it was positioned as a product that would replace traditional backup software. But that prophesy never materialized. Here's how CDP is being used today.

When continuous data protection (CDP) emerged a few years ago, it was positioned as a product that would replace traditional data backup and recovery software. Continuous data protection vendors predicted storage managers would abandon their age-old weekly full and daily incremental backups and adopt CDP, which captures every data change and can restore data and applications to any granular point in the past. But that prediction never materialized. The majority of CDP pioneers, such as the vendors Kashya, Lasso Logic Inc., Mendocino Software, Revivio and TimeSpring, were either acquired or went out of business. In addition, most storage managers continue to rely on traditional data protection vendors for backup and recovery. Does this mean continuous data protection has failed? Or is it succeeding in ways most observers wouldn't have expected?

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While the CDP acronym is familiar to many, it's interpreted in different ways. "There has been a lot of confusion about CDP and what CDP really is," said Laura Dubois, program director, storage software at IDC, Framingham, Mass. "CDP is like video and snapshots are like photos," explained Lauren Whitehouse, Enterprise Strategy Group analyst. As a result, CDP minimizes the loss of data in case of a failure. With snapshots, all data between a failure and the latest snapshot is lost.

CDP can reduce data backup windows, meet RTOs

With rapid data growth, meeting backup windows is a challenge for storage managers. This problem can be addressed with continuous data protection. CDP eliminates the need for a designated backup window as changes are captured on an ongoing basis. Similarly, the need for more aggressive recovery time objectives (RTOs) and recovery point objectives (RPOs) can be met by CDP. "There's a clear need in the data protection market for more compressed recovery points and times, which CDP helps to achieve," said Dubois.

Data protection for branch offices has been a pain point for most companies. Inadequate data protection stems from the lack of IT staffing in remote offices, the need to deploy tape libraries and the use of non-IT staff for tasks such as tape changes. Unlike expensive array-based replication, continuous data protection has installed relatively inexpensive CDP agents on remote servers, replicating data changes back to a central data center. Because these changes are replicated as they occur, bandwidth requirements are modest.

CDP has been very successful in the disaster recovery (DR) market. In a typical DR setup, production data and applications are mirrored to standby servers in a DR location to which users can be failed over quickly. Unlike array-based snapshots and replication, which have been primarily used for this in the past, continuous data protection is less expensive and less complex to set up. As a result, continuous data protection enables smaller companies to put in place a DR strategy that only larger firms could afford in the past.

"We chose CA XOsoft High Availability [formerly CA XOsoft WANSync HA] as our DR solution, because it was relatively inexpensive and has built-in provision for DR testing," said Peter Haas, director of technology at the Supreme Court in Louisiana. Asempra Technologies Inc., CA XOsoft, Double-Take Software Inc. and InMage Systems Inc. have opted for CDP as the underlying technology to power their DR-centric data protection products. "A combination of local backups and DR with the ability for failover is the best way of ensuring 24/7 availability, and CDP is the most appropriate technology to achieve it," explained Rajeev Atluri, CTO and senior VP of engineering at InMage.

Some customers have been using continuous data protection for operational reasons. "Although the primary reason for deploying InMage DR-Scout was disaster recovery, it's a great tool for cloning production instances for testing of patches and other changes prior to production migration," said Matt Reynolds, CIO at the San Francisco law firm of Howard Rice Nemerovski Canady Falk & Rabkin.

Besides continuous protection of files, continuous data protection can protect a few critical applications. Almost all CDP products protect Microsoft Exchange Server and Microsoft SQL Server, but the level of recoverability varies with each product. While some products can only recover complete Exchange storage groups and databases, others can recover single mailboxes and even single mail objects.

"Besides being able to reduce the dependency on tapes for backup and recovery, the ability to provide low-cost local disaster recovery of our Exchange servers and the ability to restore single mailboxes were the main reasons for deploying Asempra Business Continuity Server," said Derek Kruger, IT and communications supervisor for the city of Safford, Ariz.

Application support beyond Exchange and SQL Server is sparse and varies by CDP vendor. Oracle databases, IBM DB2, MySQL, Active Directory and Windows SharePoint Services are among the applications supported by some vendors. The list of supported applications proves that Windows is currently the widest supported platform for CDP. While all continuous data protection vendors support Windows, support for Unix derivatives is mostly present in higher end CDP solutions such as EMC RecoverPoint, InMage DR-Scout and Symantec Veritas NetBackup RealTime Protection.

This article originally appeared in Storage magazine.

About this author: Jacob Gsoedl is a frequent contributor to "Storage" magazine.

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