What is the main difference between a multi-datasource and an Active GridLink datasource?
A.
There is no difference. They are just different terms referring to the same construct and
capability.
B.
An Active GridLink datasource is able to respond to FAN events to provide Fast Connection
Failover (FCF), Runtime Connection Load-Balancing (RCLB), and RAC instance graceful
shutdown.
C.
An Active GridLink datasource is designed specifically for Exadata and cannot be used with any
other RAC database.
D.
A multi-datasource is meant to work only with non-Oracle high-availability datasources.
Explanation:
http://www.oracle.com/technetwork/middleware/weblogic/gridlink-rac-wp-494900.pdf
(Active Gridlink for Rac, first paragraph)
* (FAN) With Active GridLink, WebLogic subscribes to the database’s Fast Application Notification
(FAN) events using Oracle Notification Services (ONS). This allows the
WebLogic connection pool to make more informed runtime load-balancing decision based on the
current workload of each RAC node. By sending database calls to the node with lowest current
workload, the average latency of user request/response times is reduced.
* (FCF) Additionally, Active GridLink uses Fast Connection Failover (FCF), which also uses the
notification events, to enable rapid database failure detection for greater application resilience.
This feature also eases the system management overhead by allowing
WebLogic to automatically reconfigure its connection pool, in the event of planned additions or
removals of RAC nodes.
Note: A new technology component has been added to WebLogic Server on Exalogic called
‘Active
GridLink for RAC (Real Application Clusters)’. Active GridLink for RAC provides optimized
WebLogic-to-Oracle RAC database connectivity by interfacing WebLogic Server directly with the
Oracle RAC protocols. This new technology supersedes the existing WebLogic Server capability
commonly referred to as ‘Multi-Data-Sources’. Active GridLink for RAC provides more intelligent
load-balancing across RAC nodes based on the current workload of each RAC node, faster
connection failover if a RAC node fails and more transparent RAC node location management.
Active GridLink is also able to handles global transactions more optimally, where multiple
individual database operations have been encapsulated into a single atomic transaction, by the
enterprise Java application. The net effect is, for enterprise Java applications involving intensive
database work, applications achieve a higher level of availability with better throughput with
reduced and more consistent response times. In addition to the performance benefits, Active
GridLink for RAC (figure 3), also simplifies the configuration of Data Sources in WebLogic Server,
reducing the number of configuration artifacts required for Oracle RAC connectivity and mostly
eliminating RAC Service configuration changes from having a corresponding change in WebLogic
Server.
Oracle Exalogic Elastic Cloud: Software Overview, Oracle White Paper
B