14.3. Diagnostic Sources
Database problems are unavoidable. No matter how well your system may be configured and managed, problems will still occur. As an Oracle DBA, it is your responsibility to resolve database issues in a timely manner to ensure maximum database uptime. To do this, you need to be aware of the diagnostic data that Oracle provides to aid in the troubleshooting process.
The alert log provides a high-level record of the significant events that occur in a database instance. It is not relegated to strictly logging errors. The alert log is an excellent source of diagnostic data and is generally considered the first place to check when an error occurs.
When more detailed diagnostic data is required, Oracle's tracing functionality ...