This FAQ topic continues to bounce around, suggesting that this needs to be called out explicitly:
EBS concurrent managers do not need to be installed on database servers any more.
Nick Quarmby correctly noted this as one of five common mistakes that customers make when installed the E-Business Suite:
COMMON ERROR #2: Placing concurrent processing services and the database tier on the same node to improve performance. ORACLE’S RECOMMENDATION: There is no significant performance benefit to placing concurrent processing and the database tier on the same node. Your system will be more scalable if your database tier hardware is dedicated solely to serving the needs of the database. Patching, cloning and E-Business Suite administration will also be much easier as you will have at least one less APPL_TOP and application tier technology stack to maintain. Placing concurrent processing on the database tier node to distribute load might suggest that your application tier hardware is already undersized. You should place concurrent processing on the same nodes as your web/forms services or create a dedicated concurrent processing tier in exceptionally busy environments.
Where is this correctly documented?
This is currently noted in our official documentation here:
2.6 Updated Architectural Guidance With fast local networks and the typical co-location of database and application tier machines, it is now generally preferable to perform concurrent processing on a separate machine from the database. This facilitates ease of management and maintenance, and provides deployment flexibility.
This is updated guidance is already reflected in our 12.1.3 Concepts Guide and Installation Guides, and will continue to be included in future versions of our documentation.
A shibboleth of sorts
Interestingly, this question is a bit of a shibboleth in the EBS sysadmin community. DBAs who instinctively place the concurrent processing server on the same physical server as the database have been around a long time -- before gigabit network speeds made the placement irrelevant.
In fact, sharp-eyed readers might notice that this is incorrectly-documented even in some versions of our official R12 Installation Guides, which may state erroneously: "Batch Processing services must be installed on the same node as the database."
This is a documentation artifact from a bygone time. This guidance doesn't apply any longer.