For better diagnosis and resolution of critical errors Oracle 11g introduced two concepts for Oracle database called Problems and Incidents. A critical error is such as Ora-00600 and other severe errors such as Ora-07445(OS Exception) or Ora-04031(Out of memory in the shared pool portion) is known as problem. Problems are tracked in the Automatic Diagnostic Repository (ADR). This repository can be accessible even the database is down as it is stored out of the database.
Each problem is identified with a problem key which is a text string that describes the problem. The problem key includes the error code (Such as ORA 600) and in some cases, one or more error parameters values and other information.
Incident is a single occurrence of a problem and it becomes multiple times, an incident will be created for each occurrence. Incidents are timestamped and tracked in the Automatic Diagnostic Repository
An incident indentified by a numeric incident ID, which is unique to ADR. The following activities are performed during an incident.
- It records an entry in the alert log.
- An incident alert sends to OEM
- Gathers the first-failure diagnostic data about the incident in the form of trace files.
- Tags the diagnostic data with the incident ID.
- Stores the data in an ADR subdirectory created for that incident