what is the best strategy for deployment of Oracle Enterprise Manager?

For a large heterogeneous environment with a large number of hosts requiring scalability and
efficiency, what is the best strategy for deployment of Oracle Enterprise Manager?

A.
Use a centralized control with persistent connections to all agents to pull data.

B.
Use multiple semi-autonomous agents collecting information and periodically relaying it to a
central repository.

C.
Use multiple Instances of Oracle Enterprise Manager to maximize performance.

D.
Use centralized alert filtering.

Explanation:
Oracle Enterprise Manager 11g Grid Control has the ability to scale for hundreds of
users and thousands of systems and services on a single Enterprise Manager implementation.
Can use two instances of Oracle Enterprise Manager for large deployments (10000 clients or
more).
The architecture for Oracle Enterprise Manager 10g Grid Control exemplifies two key concepts in
application performance tuning: distribution and parallelization of processing. Each component of
Grid Control can be configured to apply both these concepts.
The components of Enterprise Manager Grid Control include:
* The Management Agent – A process that is deployed on each monitored host and that is
responsible for monitoring all services and components on the host. The Management Agent is

also responsible for communicating that information to the middle-tier Management Service and
for managing and maintaining the system and its services.
* The Management Service – A J2EE Web application that renders the user interface for the Grid
Control Console, works with all Management Agents to process monitoring and jobs information,
and uses the Management Repository as its data store.
* The Management Repository – The schema is an Oracle Database that contains all available
information about administrators, services, and applications managed within Enterprise Manager.
Reference: Oracle Enterprise Manager Administration, Sizing Your Enterprise Manager
Deployment