What is Automatic Diagnostic Repository?

In Oracle Database 11g, all diagnostic data is consolidated into the new Automatic Diagnostic
Repository (ADR). The database stores the ADR under the ADR base directory. The new initialization
parameter DIAGNOSTIC_DEST sets the default location of the ADR base directory. The following is how
the database determines the value of the DIAGNOSTIC_DEST parameter, if you don’t explicitly set the
parameter.

 If you set the ORACLE_BASE environment variable, the default value of the DIAGNOSTIC_DEST
parameter is the same as the value of the ORACLE_BASE variable.


 If you haven’t set the ORACLE_BASE environment variable, the default value of the
DIAGNOSTIC_DEST parameter is set to $ORACLE_HOME/log.