RMAN Key Points:
- RMAN (Recovery Manager)
- Oracle Database backup and recovery automation
- It Introduced in Oracle 8i version
- It performs block level backup
- Parallelism
- Detecting corruption in datafiles
- Validating the backup
- Incremental Backup
- Recovery Catalog etc
- Multi Destination Backups
- Archive log mode is must to use RMAN
RMAN is faster because it takes block level backups.
RMAN is faster because we can initiate parallel processes.
RMAN will data block corruptions and repair it for you.
RMAN stores backup metadata information in the database control file, you can also store the information into deferent database on different server which is called as RECOVERY catalog
RMAN Incremental Recovery
- Level 0 - Full database backup
- Level 1 - Backup of only changed blocks taken by referring data block header for updated SCN
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- As per recovery, we must only restore the database from level 0 and recovery the Database using level 1. When you try to take level 1 backup, RMAN checks if already you have level 0 backup or not. If not then it will take level 0 backup automatically.
Recovery is of two parts:
- Restore and Recover - We cannot perform recovery without restore. Hence Level 0 is used for restore and level 1 is used for recovery.
RMAN configuration Items
- show all;
RMAN Utility:
RMAN utility comes with Oracle Binaries
No special installation or license required for using RMAN
At command prompt just type rman
It defaults connects to database environmental variables defined
RMAN utility can be used only when your DB is in at least MOUNT stage
RMAN is used while the DB is up and running and have very little performance impact if the backup is running
RMAN Backup Methodology:
- Full Backup
- Entire Database backup plus archive logs
- Cannot apply Incremental backup on full backup
- Incremental Backup
- Level 0 - FULL Database backup
- Level 1 - Backup changes only from last incremental backup
- Differential Backup
- Cumulative Backup
Components of RMAN:
- RMAN Prompt
- Target Database
- Recovery Catalog
- Auxiliary Database --- When cloning, Clone DB is called as auxiliary Database
- Media Management Layer --- layer between RMAN 3rd part vendor backup tools netbackup, Veritos and Tape backups
- RMAN Channels
RMAN Configuration Parameter:
- RETENTION POLICY - tells till what date our backup will be stored which we can use for recovery
- Redundancy -- How many backups to be retained
- Recover Window -- How many days backup to be retained
- Channels -- You can define channel to take backup to disk or tape
- Control file auto backup -- includes control file and spfile auto backup
- Parallelism -- Creates multiple processes to speed up backup
- Encryption -- to secure the backup
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