Dan's Take

ExaGrid 4.9 Adds Ability To Use Oracle RMAN Channels for Backup

Many approaches, many solutions. Which is best for you?

ExaGrid's Bill Andrews, CEO, and Chris Murphy, Marketing Manager, came by to discuss different architectures used for backup and recovery software and to introduce ExaGrid 4.9, the newest version of their product.

In ExaGrid's view, there are three different approaches to backup offered by suppliers today. For the most part, ExaGrid would say, the approaches exchange a storage problem for a computational problem.

Here's a quick review of how the company analyzes the different approaches used in backup and disaster recovery solutions:

  • Inline deduplication with scale-up target side appliances. This approach requires that the backup software examine all the data as it's scanned, deduplicate and compress the data as it goes by, and then write it out to the backup media.

    Recovery is the reverse of this process. ExaGrid would point out EMC's Data Domain, HP's StoreOnce, Quantum's DXi, and DELL's DR Series as examples of this approach. The challenge to this approach is that a great deal of processing power is needed in both the backup and recovery phases, so scaling can be a problem. The more data that must be backed up or recovered, the more processing power needed and the longer the process can take.

  • Deduplication in the backup software media server to straight disk. This approach moves the deduplication and compression into the media server. ExaGrid would point out that Symantec's NetBackup and CommVault's Simpana fit this pattern. As with the first approach, scaling can be a problem. The computationally intensive part of the backup has been moved to the media server. Once again, the more data that must be backed up or recovered, the more computational horsepower that's needed.

  • Landing zone with scale out. ExaGrid claims that it is the only supplier offering this approach. In it, a snapshot of the data is brought into the appliance server and moved directly to disk. It stays there in that form for a period of time, typically a week. Only later is it deduplicated and compressed.

    The company claims that this approach can be between 5 and 10 times faster, because the backup activity is separated from the computationally-intensive deduplication and compression activities. This also means that typical recovery operations, which usually access data saved sometime during the prior week, can access the data directly without having to process the compressed, deduplicated backup data.

ExaGrid believes that its approach moves the computational problem out and away from application and database processing, and is a better fit for the mid-market (i.e., addressing the need to backup between 10TB - 500TB of data.)

Backing up data held in an Oracle Database is the focus of the ExaGrid 4.9 release. Rather than trying to access database data directly and possibly slow application processing, ExaGrid is now using the capabilities of Oracle's Recovery Manager (RMAN) to create database snapshots, without creating an impact on application processing.

ExaGrid redirects Oracle RMAN channels so that backup data can be sent to any network attached storage (NAS) server. If a NAS share is unavailable, the backup can be re-directed to another NAS share.

Dan's Take: Walking the Tightrope by Balancing Storage and Computational Performance
ExaGrid has a point. Many suppliers of backup and disaster recovery technology don't really explain that what their products do requires large amounts of storage capacity, storage performance and computational performance. Like any zero-sum game, tradeoffs have to be made to allow both application processing to execute as needed and the backup and recovery activity to execute. Some suppliers believe that they can beat the game by moving some of the activity to an appliance server. While that can work well, it can also mean that the limited capabilities of an appliance server can extend the time required to either back up critical data or recover it after an accidental deletion or device failure.

ExaGrid can offer many customer success stories in which backup was brought under control and could execute in the window of time available. The competition also can offer many happy customers.

Which approach is best for your company? That depends upon how much data needs to be backed up, how much time is available for it and how often data must be recovered from backup files. ExaGrid appears to offer a good story to consider.

About the Author

Daniel Kusnetzky, a reformed software engineer and product manager, founded Kusnetzky Group LLC in 2006. He's literally written the book on virtualization and often comments on cloud computing, mobility and systems software. He has been a business unit manager at a hardware company and head of corporate marketing and strategy at a software company.

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