WebLogic / Oracle FMW to RAC Database connection : Using Active GridLink ?

weblogic_gridlinkOracle Weblogic Server is application server that is one of the important products from Oracle Fusion Middleware. Oracle WebLoic Server connects to database using datasource and if your database is Oracle RAC (almost all big enterprises uses RAC database for high availability at database tier), You can use one of the two options to connect

a) Multi Data Source – This is old way of connecting  Oracle WebLogic Server to RAC Database

b) GridLink – This is new and better way of connecting Oracle WebLogic (and FMW products) to RAC Database

We cover both these methods for WebLogic Server to RAC Database connection in our Oracle Fusion Middleware Training (next batch starts on 9th July, 2016. Register now for early bird discount – limited time only) , apart from this we also cover Architecture, High Availability, Disaster Recovery, Patching, Cloning, Installation, OHS-WebLogic Integration, SOA, WebCenter and lot more.

We also provide consulting services for Oracle Fusion Middleware where we recommended GridLink for WebLogic to RAC database connectivity to one of our customer.  Customer wanted to use GridLink with Weblogic 10.3.6 but with FAN option unchecked and no ONS details.

If you select GridLink, configuration screen prompts you to provide FAN & ONS details (more on ONS later).



We thought to discuss about risk of using GridLink but not providing ONS details (or do not select Enable FAN option) here but before that

Here are the features of ONS (Oracle Notification Service) and FAN(Fast Application Notification) :

  • Fast Connection Failover (FCF)
  • Runtime Connection Load-Balancing by distributing the runtime work requests to all active Oracle RAC instances, including those rejoining a cluster
  • Graceful shutdown of RAC instances
  • Abort and remove invalid connections from the connection pool

Active management of the connections in the pool is managed through the real time information that the connection pool receives from the RAC Oracle Notification Service (ONS)

According to the Bug 18467939 in WebLogic 11g (10.3.6), if you don’t configure ONS and leave option FAN unchecked then it is treated as a generic data source (that means you are literally using single instance database and not RAC).

From WebLogic Server 12c (12.1.2), a new Active GridLink Flag in the console is introduced so that it is possible to specify GridLink configuration, even if ONS is not set and FAN enabled is false.

That’s because there is a new 12c driver feature that automatically configures ONS without it being specified.

In WebLogic 11g (10.3.6) this driver is not supported therefore, active Grid link is defined as both FAN enabled true and ONS configured. If one of the information is missing,  then it is treated as generic.



Are you using WebLogic or Fusion Middleware with Oracle RAC Database and not using GridLink ?

Contact Us Need any help with your Fusion Middleware Implementation or WebLogic to RAC connection


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About the Author Atul Kumar

Leave a Comment:

Razeena says April 18, 2018

If my application supports only “failover” algorithm and want to convert all the generic datasources to GridLink to use 2 node RAC DB using weblogic , then where in Gridlink do i specify that the algorithm should be “failover”, I do not see any option to choose an algorithm type in the weblogic console while configuring gridlink , so how do i make sure that my application is configured to work using “failover” algorithm ..pls give some inputs..

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