The Automatic Diagnostic Repository (ADR) is a system-wide tracing and logging central repository for database diagnostic data. It includes the following items:

• Background trace files store information from database background processes. When a process detects an internal error, the process dumps information about the error to its trace file. Some of the information written to a trace file is intended for the database administrator, whereas other information is for Oracle Support Services. Typically, database background process trace file names contain the Oracle system identifier (SID), the background process name, and the operating system process number. An example of a trace file for the RECO process is mytest_reco_10355.trc.
• Foreground trace files store information from server processes. When a process detects an internal error, the process dumps information about the error to its trace file. Server process trace file names contain the Oracle SID, the string ora, and the operating system process number. An example of a server process trace file name is mytest_ora_10304.trc.
• Dump files are a special type of trace file that contains detailed point-in-time information about a state or structure. A dump file is typically a one-time output of diagnostic data in response to an event, whereas a trace file tends to be a continuous output of diagnostic data.
• Health monitor reports include results of diagnostic checks from the Health Monitor framework. Health checks detect file corruptions, physical and logical block corruptions, undo and redo corruptions, data dictionary corruptions, and more. The health checks generate reports of their findings and, in many cases, recommendations for resolving problems.
• Incident packages contain information for uploading diagnostic data to Oracle Support. A package is a collection of metadata that is stored in the ADR and points to diagnostic data files and other files both in and outside of the ADR. When you create a package, you select one or more problems to add to the package. The Support Workbench then automatically adds to the package the problem information, incident information, and diagnostic data (such as trace files and dumps) associated with the selected problems.
• Incident dumps contain diagnostic data that Oracle Database collects when an incident occurs. The database writes one or more dumps to the incident directory created for the incident. Incident dumps also contain the incident number in the file name.
• Alert log file is a chronological log of messages and errors. Oracle recommends that you review the alert log periodically.

• Automatic Diagnostic Repository