As Published In
Oracle Magazine
January/February 2008

COMMENT: In The Field

Succeeding with Failure

By Ari Kaplan

Oracle Data Guard helps enable disaster recovery systems—and much more.

Failure is something you probably don't like thinking about much. After all, you work hard to keep your system running 24/7, and you want to avoid the idea of it failing. Even if you're among those few who can imagine the unimaginable and plan for the contingency of a site failure, how do you sell the concept of a contingency plan for failure to management?

The difficulty with thinking about system failure is getting away from the failure concept and the cost of implementing a disaster recovery system. Instead, try to picture your ecstatic managers when, despite the massive system failure that no one saw coming, business goes on without a hitch. With that happy image as a goal, you can begin moving toward a disaster recovery system—and sell it upstairs.

Oracle Data Guard, which guards your data at a secondary target site in case something bad happens to your production site, is vital to such a scenario. If calamity strikes at your production site—be it electrical blackout, flood, forced evacuation, or anything else you see on the news every day—you want the comfort of knowing that a remote target site is waiting for you to flip the switch and save the day.

Getting data to such a target site used to be a logistical nightmare. You needed to pack up a truckful of tapes, physically move them to the alternate site, and restore data from the tapes to the standby system. And that was when database sizes were fairly modest. With today's multiterabyte databases, you'd need a fleet of trucks for your tapes.

Oracle Data Guard works differently. It runs continuously in the background, constantly moving data from the production site to the target site. The catch, of course, is that you still need to set up at least one target site to receive the data—a site that might never be used.

The cost of disaster recovery systems is not always easy to justify. However, I've worked with several companies that have implemented disaster recovery systems that get clear value beyond the "insurance" of the target system. This additional value has come when upper management mandated a disaster recovery system to meet some compliance requirement—and IT looked at this idle second system and wondered, "Hmm, what if we . . ."

One use for the target system seems obvious: to help with backups. Some people might regard a disaster recovery system as a substitute for backup, but this is a mistake. Your real backup system should be oriented toward rapidly restoring lost or damaged individual files or blocks. A disaster recovery system takes over entirely for a failed production system.

Some companies that I've helped have leveraged their target systems for backup in this way: they back up from the target system instead of the production system. The traditional method slows down the production system and interferes with real-time processing. Doing backups from the target system frees the production system from that drag on performance.

Other companies I've worked with have another convenient use for their target system. They run reporting off the target—not the production—system. Gathering all the statistics, forecasting, and business intelligence that databases can provide is vital for reporting in an organization. But gathering this data can interfere with the transaction-handling duties of the production system, sometimes significantly.

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By running reports from the target system, you again free up the production system for real-time transactions. In fact, you might be able to do more with the target system, simply because you can perform time-consuming analysis you never would have dared with your production system.

You can also use a target system to enable planned maintenance on the production system. You can perform a planned failover to the target system and let that handle the everyday database chores. Meanwhile, you can perform any necessary maintenance on the actual production system—adding or replacing hardware, upgrading operating systems, applying patches, or whatever is necessary. When the maintenance is done, you sync the two systems again and let the production system resume its usual duties. It's a simple solution to an often-vexing IT problem.

These kinds of uses for your target system should give you some talking points in selling disaster recovery to reluctant managers. So should the fact that Oracle Data Guard is free with Oracle Database Enterprise Edition. That makes disaster recovery the kind of insurance plan that pays you dividends, even while you hope you never have to collect.


Ari Kaplan ( is president of the Independent Oracle Users Group (IOUG) and a senior consultant at Datalink. He founded Expand Beyond Corporation, a leader in mobile IT software. He has been involved in Oracle technology since 1992.

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