1) Pfile: PFILE is static file or text file that contains a list of all initialization parameters. It can be edited using vi editor on Unix server or notepad on Windows. This PFILE is read during instance startup time to get specific instance parameters. 2) SPFILE: SPFILE is a binary file that contains the same information as the PFILE. It allows dynamic changes without requiring you to restart that instance. By default, SPFILE is read even though PFILE is present in the location. This file is not editable since it is binary file. You have to use "alter system" command to make any parameter changes in SPFILE. 3) Init.ora: It is sample pfile which contains ORCL database details. This file is a starting point to customize your RDBMS installation for your site. The values in this file are only intended to be used as a starting point. You have to tune those values as per your needs. 4) Password File: The password file stores authentication credentials for privileged administrative users such as SYS, SYSDBA, SYSBACKUP, SYSDG, and SYSKM. It enables these users to connect to the database remotely without depending on operating system authentication. This file is important for performing administrative tasks over the network such as Starting up or shutting down the databases, performing RMAN backups, managing Oracle Data Guard configurations, etc. Oracle uses this file when REMOTE_LOGIN_PASSWORDFILE is set to EXCLUSIVE or SHARED. If the value is NONE then, Oracle ignores password file. 5) Control Files: Control file is the critical binary file of the database that records the physical structure of the database. This contains reusable and non-reusable information like database name, names and locations of datafiles and redo log files, timestamp of the database creation, current log sequence number, checkpoint information, RMAN backups and archived logs, Information related to backup and recovery, etc. 6) Data Files: Data files contain actual database data. These contain the contents of logical database structures in database like tables and indexes. 7) Redo Log Files: The redo log is one of the most critical parts for database recovery operations. Each Redo Log Group may contain one or more redo members that store a record of all changes made to the database, including both committed and uncommitted transactions. Once the log switch occurs, redo group of filled online redo log file gets switched to next available redo log group. 8) Temp Files: Temp files are kind of data files used for sorting purpose like order by, group by, hash joins, Global Temporary Tables (GTT), etc. Temp files are associated with temporary tablespaces. Unlike regular data files that store permanent database objects (tables, indexes, etc.), temp files are used to store temporary data generated during database operations. 9) listener.ora: The listerner.ora file contains server-side network configuration parameters. Listener runs only on the server, not on the client machines. After the first database on the server is created, the listener service automatically starts. Once a new database is created, the DB network and service information is automatically added to the listener configuration file. Upon instance startup, the database registers itself automatically with the listener, and the listener starts listening for connection requests to this DB. 10) tnsnames.ora: The tnsnames.ora file is a configuration file that contains network service names mapped to connect descriptors, or net service names mapped to listener protocol addresses. A tnsnames.ora file can contain net service names with one or more connect descriptors with one or more protocol addresses. A net service name is a name mapped to a database network address in a connect descriptor. A connect descriptor contains the location of the listener with a protocol address and the service name of the database to which to connect. Clients and database servers use the net service name while making a connection with an application. 11) sqlnet.ora: The sqlnet.ora file is a profile configuration file used by both Oracle clients and database servers. On the server side, it can be used to configure access control parameters that determine whether client connections are allowed or denied based on protocols or other security rules. When the Oracle Listener service starts, it reads the sqlnet.ora file and applies the access control settings specified. By default, the sqlnet.ora file is located in the $ORACLE_HOME/network/admin directory. However, this location can be changed by setting the $TNS_ADMIN environment variable. 12) Oracle Binary Files: These are Oracle Software Binaries extracted before Oracle DB software installation activity. 13) Archive log file: Archived log file is offline copy of the online redo log file that contains all the changes made to the database. These archived log files are important for performing database recovery, especially in case of media failures or point-in-time recovery scenarios. Archived logs are generated only when the database is running in ARCHIVELOG mode to ensure that no changes are lost once they are written to the online redo logs. 14) Flashback logs: Flashback logs are used by the Flashback Database feature to rewind the database to a previous point in time without needing to perform a traditional restore and recovery operation. Flashback logs are stored within the FRA that is a dedicated location managed by Oracle. Oracle automatically manages the creation, writing, and deletion of flashback logs, you don't have to maintain them manually. 15) Change Tracking File: The Change Tracking File is used when you enable Block Change Tracking feature in the database that significantly improves the performance of RMAN incremental backups. This file records the blocks that have changed since last backup. The tracking is recorded by CTWR (Change Tracking Writer) process. 16) Listener Log File: The Listener log file is a source for monitoring and troubleshooting network connectivity to the Oracle database. It captures detailed information about client connection requests, commands issued via lsnrctl, service registration events, and other listener related activities. This log file helps us to identify connectivity issues, unauthorized access attempts, and the overall health of listener operations. 17) Alert Log: The Database Alert Log is the primary diagnostic log file used to troubleshoot critical issues in an Oracle database. It records important information such as ORA- errors, log switch activity, startup and shutdown operations, background process messages, etc. 18) XML alert log: The XML Alert Log is a copy of the traditional database alert log, but stored in XML format. While the standard alert log is in plain text format. If certain entries are accidentally deleted or modified in the text-based alert log, the original information can still be retrieved from the XML alert log, making it a reliable backup for auditing and troubleshooting purposes. 19) trc and trm files: Trace files (.trc) are generated by both foreground and background processes in the Oracle database. Trace files record detailed information about internal operations, ORA- errors, and events which are essential for diagnose performance analysis and event tracing. Trace files provide in-depth diagnostics when specific events or parameters are set in the database. The trm files are associated with trace files and contain metadata about the corresponding trace files. 20) Export Dump Files: An export dump file in Oracle Database is a set of operating system files created by Oracle export utility. The dump generated by expdp can only be understood by impdp utility. Dump files contain binary format that stores data as well as metadata of database objects like tables, indexes, procedures, functions, etc. 21) Backup Files: Backup files are physical files created by RMAN backup, OS backups (CP). |
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