Redo Log History All transactions are recorded in the online redo log files. This allows for automatic recovery of transactions in the event of a database failure. If the database is configured for NOARCHIVELOG mode, no redo history is saved to archived log files, and recovery operations are limited and a loss of transaction work may occur. This is the result of the automatic recycling of log files, where older log files needed for recovery are overwritten and only the most recent part of the transaction history is available. You can configure a database in ARCHIVELOG mode, so that a history of redo. | Configuring the Database Archiving Mode Objectives After completing this lesson, you should be able to do the following: Describe the differences between ARCHIVELOG and NOARCHIVELOG modes Configure a database for ARCHIVELOG mode Enable automatic archiving Perform manual archiving of logs Configure multiple archive processes Configure multiple destinations, including remote destinations Online redo log files No redo history LGWR Redo history 054 053 052 Redo Log History 051 052 Redo Log History All transactions are recorded in the online redo log files. This allows for automatic recovery of transactions in the event of a database failure. If the database is configured for NOARCHIVELOG mode, no redo history is saved to archived log files, and recovery operations are limited and a loss of transaction work may occur. This is the result of the automatic recycling of log files, where older log files needed for recovery are overwritten and only the most recent part of the transaction history is available. You can configure a database in ARCHIVELOG mode, so that a history of redo information is maintained in archived files. The archived redo log files can be used for media recovery. The database can be initially created in ARCHIVELOG mode, but it is configured for NOARCHIVELOG mode by default. Online redo log files No redo history 053 LGWR 054 053 052 053 054 053 052 052 NOARCHIVELOG Mode NOARCHIVELOG Mode By default, a database is created in NOARCHIVELOG mode. The characteristics of operating a database in NOARCHIVELOG mode are as follows: Redo log files are used in a circular fashion. A redo log file can be reused immediately after a checkpoint has taken place. After redo logs are overwritten, media recovery is only possible to the last full backup. Implications of NOARCHIVELOG Mode If a tablespace becomes unavailable because of a failure, you cannot continue to operate the database until the tablespace has been dropped or the entire database has been restored from . | Configuring the Database Archiving Mode Objectives After completing this lesson, you should be able to do the following: Describe the differences between ARCHIVELOG and NOARCHIVELOG modes Configure a database for ARCHIVELOG mode Enable automatic archiving Perform manual archiving of logs Configure multiple archive processes Configure multiple destinations, including remote destinations Online redo log files No redo history LGWR Redo history 054 053 052 Redo Log History 051 052 Redo Log History All transactions are recorded in the online redo log files. This allows for automatic recovery of transactions in the event of a database failure. If the database is configured for NOARCHIVELOG mode, no redo history is saved to archived log files, and recovery operations are limited and a loss of transaction work may occur. This is the result of the automatic recycling of log files, where older log files needed for recovery are overwritten and only the most recent part of the transaction history
