Parameter file Contains a list of initialization parameters that control how certain aspects of the database instance behave. Most parameters can be modified without restarting the instance, while some require that it be shut down and restarted to pick up the new values. Also known as the initialization file.
2. Password file
Password file Stores passwords in an encrypted format for certain privileged users who are allowed to start and stop the database. Normally, when users connect to the database, their privileges are verified from within the database itself. Since the database is unavailable when it is not running, a privileged user who is starting the database must be authenticated by some other means. The password file provides this capability by storing the privileged user’s password outside of the database.
3. Alert log:
Alert log Records all internal errors and information about several database operations. The DBA should check the alert log at least once a day. The alert log entry briefly describes an error and provides the name of a trace file, which contains more detailed information regarding the internal errors.
