The Oracle Enterprise Manager

The Oracle Enterprise Manager is a tool that helps users manage and monitor Oracle Servers. The following components are part of OEM. Note that these components are largely relevant to commercial Oracle server installations.

• The OEM Console is a GUI front end to Oracle. Users may schedule and automate jobs such as backups, start up, shut down, etc.; define events; monitor the database; and create, manage, and modify various database objects such as tables, views etc., through the console. The console may be configured to open databases on remote locations across the network.
• The Oracle Intelligent Agent (OIA) runs on the database itself. Jobs and events scheduled through the Console are executed through the OIA
• The Oracle Management Server (OMS) is the interface between the OEM console and intelligent agents that execute jobs. The OEM Console may be connected to a management server (rather than opened in standalone mode) to monitor and configure the Oracle Enterprise Edition.

The Oracle Management Server is a new component on the OEM architecture. A typical two-tier architecture involves a client machine and a server that fulfills requests from the client machine. The new version of OEM is modeled after a 3-tier architecture of Client, Management Server, and Application. Processing and communication is now performed on the middle tier by the Management Server. The OMS communicates with the Intelligent Agent and stores information in a OEM Repository. The OEM Client connects to the OMS to retrieve information from the OEM repository.

Figure 2a: OEM Architecture (From oracle.com)

 OMS allows the management of multiple databases from a single system. An OMS has special links with a repository database that is used to store its details. The repository consists of a set of tables that store state information (i.e. look and feel, database connections etc.) for the environment being managed. The repository is used as a back-end store by the OMS to interface between the OEM client and each managed node or database. The idea is that each user or DBA creates a repository on the OMS. Logging into the management server just opens a specific DBA's repository. Thus, each DBA's console display is limited to the nodes he manages and information about their state. OMS setup is automatically performed during installation. The steps will include the creation of a new repository. The userid 'SYSMAN' and password 'oem_temp' should be used when logging onto the management server for the first time.