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The increasing size and complexity of IT installations makes management a challenging task. This is hardly surprising: no one ever said that managing a powerful environment should necessarily be simple. However, management tools can make the task easier and the management staff more productive.
Oracle Enterprise Manager comes in three forms:
Database Control
Application Server Control
Grid Control
Oracle Enterprise Manager Database Control is a graphical tool for managing one database, which may be a RAC clustered database. It consists of a Java process running on the database server machine. Administrators connect to Database Control from a browser, and Database Control then connects to the database server.
Database Control has facilities for real-time management and monitoring, running scheduled jobs, and reporting alert conditions interactively and through e-mail. Oracle Enterprise Manager Application Server Control is a graphical tool for managing one application server instance or a group of instances. The grouping technology is dependent on the version. Up to Oracle Application Server 10g release 2, multiple application servers were managed as a “farm,” with a metadata repository (typically residing in an Oracle database) as the central management point. From release 3 onward, the technology is based on J2EE clustering, which is not proprietary to Oracle.
Oracle Enterprise Manager Grid Control globalizes the management environment. A management repository (residing in an Oracle database) and one or more management servers manage the complete environment: all the databases and application servers, wherever they may be. Grid Control can also manage the nodes, or machines, on which the servers run, as well as (through plug-ins) a wide range of third-party products. Each managed node runs an agent process, which is responsible for monitoring the managed target on the node: executing jobs against them and reporting status, activity levels, and alert conditions back to the management server(s).
Grid Control gives a holistic view of the environment and, if well configured, makes administration staff far more productive than they are without it. It becomes possible for one administrator to manage effectively hundreds of targets.