ADDM Enhancements in Oracle Database 11g

Oracle Database 10g introduced the Automatic Database Diagnostic Monitor (ADDM) feature set as part of the Diagnostic Pack, and it’s proved to be a flexible scalpel for pruning away nonrelated issues during both reactive and proactive instance performance tuning. This article illustrates how Oracle Database 11gR1 has expanded ADDM to encompass Real Application Clusters (RAC) database tuning at the global level and provides the ability to filter out previously identified performance issues from any ADDM analysis report.

http://www.dbasupport.com/oracle/ora11g/ADDM-Enhancements-01.shtml