Oracle Enterprise Manager (OEM) is a set of systems management tools provided by Oracle Corporation for managing the Oracle environment. It provides tools to monitor the Oracle environment and automate tasks (both one-time and repetitive in nature) to take database and application administration a step closer to "Lights Out" management.
 Web Based Enterprise Manager
 Database control
Oracle Enterprise Manager application for managing a single Oracle Database.
Database Control was first introduced with Oracle 10g and is installed with the database software.
 Grid control
Oracle Enterprise Manager's web based interface for centrally managing all your Oracle environments from a single point.
 EM Agents
Agents can be installed on servers to collect data to feed into Grid control. To manage the agent:
CMD>set ORACLE_SID=sid CMD>emctl stop agent CMD>emctl start agent CMD>emctl status agent
 GUI Based Enterprise Manager
Shipped with the Oracle "client CD". Select a "Administrator" type install.
Some options, like the Replication Manager is only available with the GUI version.
 Management packs
The following management packs are available. These packs must be separately licensed. Also note that these packs are only available for Oracle Enterprise Edition (EE). So, if you are running Standard Edition (SE), and you want to use one of these packs, you will have to licence and upgrade to EE first (strange, but true!).
 Oracle Configuration Management Pack
Track hardware and software configuration for hosts and databases plus cloning for database instances and Oracle home to facilitate deployments.
 Oracle Change Management Pack
Evaluate, plan for, and implement database schema changes to support new application requirements; eliminate errors/data loss when making changes; minimize downtime.
 Oracle Diagnostics Pack
Ensure high availability of mission-critical business systems by reducing the number of complex performance tasks.
 Oracle Tuning Pack (requires Diagnostics Pack)
Dynamic tuning recommendations for more-efficient resource utilization, higher transaction throughput, faster query performance; avoid costly hardware, memory, and disk upgrades.
OEM creates a SYSMAN schema in the Oracle database to store metadata and statistics. SYSMAN also acts as the super-administrator account for first-time login. The default password for SYSMAN is oem_temp.
To create a new DBControl repository:
emca -config dbcontrol db -repos create
To start a DB Console:
emctl start dbconsole