Automatic Diagnostic Repository

The ADR root directory is known as ADR base. Its location is set by the DIAGNOSTIC_DEST initialization parameter. If this parameter is omitted or left null, the database sets
DIAGNOSTIC_DEST upon startup as follows:
- If environment variable ORACLE_BASE is set, DIAGNOSTIC_DEST is set to the directory designated by ORACLE_BASE.
- If environment variable ORACLE_BASE is not set, DIAGNOSTIC_DEST is set to ORACLE_HOME/log.

Within ADR base, there can be multiple ADR homes, where each ADR home is the root directory for all diagnostic data—traces, dumps, the alert log, and so on—for a particular instance of a particular Oracle product or component. For example, in an Oracle Real Application Clusters environment with ASM, each database instance and each ASM instance has an ADR home. All ADR homes share the same hierarchical directory structure.

The location of an ADR home is given by the following path, which starts at the ADR base directory:

diag/product_type/product_id/instance_id

Path Component	Value for Oracle Database
product_type	rdbms
product_id	database name
instance_id	SID

For example, for a database with a SID and database name both equal to edba01, the ADR home would be in the following location:

ADR_base/diag/rdbms/edba01/edba01/


ADR Home Subdirectories

Within the ADR home directory are subdirectories where the database instance stores diagnostic data.

Subdirectory Name	Contents
alert	The XML-formatted alert log
cdump	Core files
incident	Multiple subdirectories, where each subdirectory is named for a particular incident, and where each contains dumps pertaining only to that incident
trace	Background and server process trace files and SQL trace files
(others)	Other subdirectories of ADR home, which store incident packages, health monitor reports, and other information

ADR in an Oracle Real Application Clusters Environment

In an Oracle Real Application Clusters (RAC) environment, each node can have ADR base on its own local storage, or ADR base can be set to a location on shared storage. The following are the advantages of the shared storage approach:
- You can use ADRCI to view aggregated diagnostic data from all instances on a single report.
- You can use the Data Recovery Advisor to help diagnose and repair corrupted data blocks, corrupted or missing files, and other data failures. (For Oracle RAC, the Data Recovery Advisor requires shared storage.)