Oracle10g Enterprise Manager (EM) has a fantastic interface for easily creating exception alerts and mailing them directly to the Oracle professional. However, the EM has limitations. Until EM evolves into a true Decision Support System (DSS) for the Oracle DBA, the DBA will still need to extract and use the workload information stored in the AWR (Advanced Workload Repository).
Advisors are the server components that provide you with useful feedback about resource utilization and performance. The most important of all advisors is the Automatic Database Diagnostic Monitor (ADDM). ADDM does analysis of the system, identifies problems and their potential causes, and comes up with recommendations for fixing the problems. It can call all other advisors also.
Just a few years ago, many senior Oracle DBAs detested Oracle Enterprise Manager (EM). Viewed as a crutch for beginners who could not memorize the command syntax, EM was largely ignored by the veteran DBA who preferred the ease and certainty of the SQL*Plus command-line interface. This is about to change.