Applications

Node Affinity. Interesting usage of Oracle RAC with E-Business Suite

Oracle RAC (Real Application Cluster) is used generally in a High Availability (HA 24/7 availability—Provide continuous uptime for database applications) and/or Scalability (Expand capacity by simply adding servers to your cluster) context. But another very useful but not wellknown but extremely interesting context is the NODE AFFINITY (called “Application Affinity” too).

We can implement Application Affinity mode :

• When multiple workload needs to share the same database (to avoid replication/cloning) in parallel with the need to protect wokloads from each other. Exemple : OLTP in parallel with a big Batch or BI users.

• To have load balancing on Application Tiers server and to connect them to specific DB Instances.
• For Concurrent Manager jobs to minimize Interconnect traffic and maximize the performance of the concurrent request. For example Order Import(Order management)requests run on Standard Manager1 which connects to Db Node1 and Pick Release (Inventory) run on DB node2.

Node Affinity concept is often used to isolate Discoverer users and EBS OLTP users. Certain Oracle OnDemand customers implemented the “TWIN-RAC” (name used internally) concept 2 x 2 nodes (4 Oracle RAC nodes implementation):
- 2 nodes for EBS : 1 for OLTP users and 1 node for Batch (concurrent manager)
- 2 nodes for Discoverer: 1 node 100% discoverer users and the last node is used by discoverer users during the day but during the night and end month closing period we are using this node for certain specific concurrent program.

I recommend to use Oracle Service in place as standard hostname/ip/port/SID to increase availability and the possibility to use load balancing. Another interesting point is the usage of Virtual hostname to improve failover time. To have more information on Oracle service you can see several examples into the document of my collegue Frederic Michiara page 323 (15.5 Creating Oracle Services) and regarding the implementation of VIP you can see the metalink Note 356433.1 “Using Oracle Applications Release 11i with Virtual Hostnames and Business Continuity” and
Note.302738.1 “Using Virtual Hostnames with Oracle Applications Release 11i:”
You can find here “Optimizing the E-Business Suite with Real Application Clusters (RAC)” a fantastic document written by Ahmed Alomari, Cybernoor where the usage of Application Affinity is explained in details.

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