DIAGNOSTIC_DEST

Property	Description
Parameter type	String
Syntax	`DIAGNOSTIC_DEST = { pathname \| directory }`
Default value	Derived from the value of `ORACLE_BASE ($ORACLE_BASE)`. If the `$ORACLE_BASE` environment variable does not exist, then `$ORACLE_HOME` is used.
Modifiable	`ALTER SYSTEM`
Basic	No
Real Application Clusters	This parameter can be set on each instance. Oracle recommends that each instance in a cluster specify a `DIAGNOSTIC_DEST` directory location that is located on shared disk and that the same value for `DIAGNOSTIC_DEST` be specified for each instance.

As of Oracle Database 11g Release 1, the diagnostics for each database instance are located in a dedicated directory, which can be specified through the DIAGNOSTIC_DEST initialization parameter. The structure of the directory specified by DIAGNOSTIC_DEST is as follows:

<diagnostic_dest>/diag/rdbms/<dbname>/<instname>

This location is known as the Automatic Diagnostic Repository (ADR) Home. For example, if the database name is proddb and the instance name is proddb1, the ADR home directory would be <diagnostic_dest>/diag/rdbms/proddb/proddb1.

The following files are located under the ADR home directory:

Trace files - located in subdirectory <adr-home>/trace
Alert logs - located in subdirectory <adr-home>/alert. In addition, the alert.log file is now in XML format, which conforms to the Oracle ARB logging standard.
Core files - located in the subdirectory <adr-home>/cdumd
Incident files - the occurrence of each serious error (for example, ORA-600, ORA-1578, ORA-7445) causes an incident to be created. Each incident is assigned an ID and dumping for each incident (error stack, call stack, block dumps, and so on) is stored in its own file, separated from process trace files. Incident dump files are located in <adr-home>/incident/<incdir#>. You can find the incident dump file location inside the process trace file.