Oracle Clusterware ADR data is written under a root directory known as the ADR base. Because components other than ADR use this directory, it may also be referred to as the Oracle base. You specify the file system path to use as the base during Oracle Grid Infrastructure installation and can only be changed if you reinstall the Oracle Grid Infrastructure.
ADR files reside in an ADR home directory. The ADR home for Oracle Clusterware running on a given host always has this structure:
ORACLE_BASE/diag/crs/host_name/crs
In the preceding example, ORACLE_BASE is the Oracle base path you specified when you installed the Oracle Grid Infrastructure and host_name is the name of the host. On a Windows platform, this path uses backslashes (\) to separate directory names.
Under the ADR home are various directories for specific types of ADR data. The directories of greatest interest are trace and incident. The trace directory contains all normal (non-incident) trace files written by Oracle Clusterware daemons and command-line programs as well as the simple text version of the Oracle Clusterware alert log. This organization differs significantly from versions prior to Oracle Clusterware 12c release 1 (12.1.0.2), where diagnostic log files were written under distinct directories per daemon.