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How to license Oracle’s Data Guard vs Active Data Guard?

SoftwareOne blog editorial team
Blog Editorial Team
Publisher advisory

Many end users make use of a disaster recovery (DR) solution in which data is copied from the primary production database to the secondary disaster recovery database. Often, end users either make use of the functionalities of Data Guard or Active Data Guard to achieve such a solution. But how does licensing Data Guard and Active Data Guard work? And does the installation of the Data Guard Observer on a license require you to license the Oracle Database? This since Oracle states in its license agreements that the software is required to be licensed, once the software is “installed and/or running”. In order to answer these questions, we should first have a clear view of the differences between Data Guard and Active Data Guard.

Data Guard vs. Active Data Guard

The Data Guard feature provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions. Data Guard maintains these standby databases as transactionally consistent copies of the production database. Data Guard is a feature of the Oracle Database Enterprise Edition itself and does not require separate licensing.

On the other hand, Active Data Guard is a so-called Oracle Database Enterprise Edition Option and as such requires separate licensing. Active Data Guard was introduced with Oracle Database 11g Release 1 to provide important extensions to basic Data Guard functionality that further enhance data protection, availability, and return on investment (ROI) in standby systems. To be concrete both the primary production server and the secondary DR server are required to be fully licensed and the same license metric should be applied as to the associated licenses for the Oracle Database itself.

Active Data Guard includes a number of features and functionalities, such us:

  • Real-Time Query to offload read-only workloads to an up-to-date standby database. This adds capacity, improves response time, and increases return on investment. It also provides continuous validation that the standby database is production-ready.
  • Automatic Block Repair to transparently repair physical corruptions wherever they occur, at either the primary or standby database.
  • Far Sync to enable zero data loss protection and off-host network compression, even when primary and standby are hundreds or thousands of miles apart.
  • RMAN Block Change Tracking to offload fast incremental backups to an Active Data Guard Standby with 20x the performance of traditional incremental backups.
  • Active Data Guard Rolling Upgrade to make it simple to reduce planned downtime and minimize the risk of introducing changes to production systems.
  • Global Database Services to provide intelligent load balancing and automated service management across replicated databases.
  • Application Continuity to make outages transparent to users by reliably handling in-flight transactions.

Active Data Guard is an evolution of Data Guard technology that improves production database performance for critical transactions. As such, both Active Data Guard and Data Guard are related technologies, but their use results in different licensing requirements.

But what is Data Guard Observer?

Data Guard Observer is a component of the Oracle Data Guard command-line interface which monitors the availability of the primary database. The Observer continuously monitors the fast-start failover environment to ensure the primary database is available. You can achieve a reduction in downtime or zero downtime and maintain user connectivity to the primary system active by using Data Guard Observer. Installing and starting the Observer is an integral part of using fast-start failover.

In order to use fast-start failover (FSFO) you must install DGMGRL (Data Guard Broker Command Line Interface) and run the Observer software. So, fast-start failover is a feature of Oracle Data Guard and cannot run without a Data Guard Broker configuration. Only one Observer can be observing the broker configuration at any given time. You have to use the DGMGRL command to determine the location of the Observer that is currently associated with the broker configuration.

If the Observer’s host machine crashes, the broker configuration is no longer observed and fast-start failover is no longer possible. In this case, you may have to move the Observer to a new host if the original host machine cannot be repaired in a timely fashion. To move the Observer, you must stop allowing the first Observer to observe this broker configuration, and then start a new Observer.

Starting with Oracle 12cR2 it is possible to configure multiple Observers within a single Oracle Data Guard broker configuration. Multiple Observers provide an immediate benefit for High Availability. If one Observer fails, there are additional Observers that can continue to monitor the status of the configuration.

The Data Guard Observer model, source: Oracle

Do I require a license for the client itself?

As per Oracle’s program documentation, the Client software (to connect with the Oracle Database) can be installed separately on the specific end user device that connects to the Oracle Database. The installation of the Oracle Client itself as such does not require separate licensing, as long as the Oracle Database itself as installed on a server is licensed with sufficient Named User Plus and/or Processor licenses.


Although (a) the Oracle Data Guard Observer can be installed on a client and (b) the licensing rules of Oracle state that the software is required to be licensed if it is installed and/or running, the installation of the Oracle Dataguard Observer itself does not require separate licensing.

This since Data Guard Observer is a feature of the Oracle Database itself and the Client software itself is free of use. As long as the primary production server and secondary disaster recovery server are fully licensed and per the same license metric as the associated Oracle Database, then there is nothing to worry about from a licensing perspective.

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Watch Out!

As with many software licensing matters, the devil is typically in the detail. Do you have a specific licensing question you require support on? Reach out today.

Watch Out!

As with many software licensing matters, the devil is typically in the detail. Do you have a specific licensing question you require support on? Reach out today.


SoftwareOne blog editorial team

Blog Editorial Team

We analyse the latest IT trends and industry-relevant innovations to keep you up-to-date with the latest technology.