Concurrent Manager should share the ride with Applications Tier Van, or hop on to the Database Van

Numerous posts are flooded across the Internet detailing the benefits of Concurrent Managers hosted on the Database Tier, as compared to the same running on the Applications tier node with its other siblings, viz. Admin tier, Web Tier, Forms tier, etc. Indeed, it has been predominantly one of the most popular debates among industry DBAs to discuss the benefits of Concurrent Server hosted on the Database Tier, vs. Applications Tier

The results of this debate has never been unanimous, and despite numerous statistics indicating Concurrent Manager not benefitting significantly from being hosted on the Database Tier, there have been far more number of reported incidents where Concurrent Manager did get benefitted in terms of response time and throughput when hosted on the Database Tier. At last, Oracle decided to make it a standard recommendation to host the Concurrent Processing with the Database Tier in a multi-tier environment, if possible

This recommendation ruled the Oracle E-Business Suite Architecture platform for quite a while, but was pulled over for a fresh round of discussion when Rel 12 came in with a new architectural layout. The reason for pulling this item out of its grave was the way Applications tier components were re-organized in the new structural layout of Rel 12. In Rel 12 which comes with Unified Appl_Top that gets installed by default, the Applications components such as Concurrent Processing, Web tier, Admin tier, Forms tier, etc. is present on all of the Applications tier nodes. On the other hand, it was possible to separate the Applications tier components till 11.5.10.2, unlike Rel 12 where difference between nodes is solely dependent on the service groups activated on the Applications tier nodes. Few of the significant service groups worth considerations could be the Root services (OPMN), Web Entry Point services (Oracle HTTP Server), Web Applications Services (OC4J Components of OACORE, Forms and OAFM), Batch Processing Services (Applications TNS Listener, Concurrent Manager, Fulfillment Server), and other Service Groups (Oracle Forms Services, Oracle MWA Services), etc.

Conclusively, the recommendation of having Concurrent Manager share the ride with Database tier, is losing ground in Rel 12 and driving the industry-experts to recommend Concurrent Processing on its own separate tier, or with the rest of the Applications tier components. Another pseudo benefit of removing Concurrent Manager from the Database tier, is an increased efficiency in the regular manageability aspects and periodic maintenance activities like patching and cloning which would need to be performed on at least one less Applications tier node

Oracle has a dedicated Document detailing about this topic in My Oracle Support with Id 406558.1