Flash recovery Area

This is from my older site oraclemiracledba , that I thought might still be useful here.

What is the Flash Recovery Area ?

The Flash Recovery Area is an area for storing certain types of files on disk. These files typically consist of flashback database logs and RMAN related files. It can be a regular file system or an ASM group. Oracle does NOT need to use a Flash Recovery Area to operate the database. It is recommended for easy of use and simplification for Backup and Recovery purposes and the associated space management. By placing files in the Flash Recovery Area, Oracle will manage the space usage, deleting files that are no longer required, when the space is required. However, if space is not required, Oracle will maintain the files on disk (as a form of cache for files backed up to tape).

Components of the Flash Recovery Area

The flash recover area can contain permanent or transient files. It can contain any or all of the following types of files:

Multiplexed copy of control file.
Multiplexed copy of online redo log.
Archived redo log files
RMAN backup sets, backup copies, etc.
Flashback logs
Of these files ONLY the flashback logs are required to be stored in the flash recovery area.



Configure Flash Recovery Area

Configuring the Flash Recovery Area is simple. Once the disk file system is mounted, or the ASM group created, all that is required is setting is to configure it by setting the two init.ora parameters related to the configuration :

· DB_RECOVERY_FILE_DEST_SIZE

· DB_RECOVERY_FILE_DEST

DB_RECOVERY_FILE_DEST_SIZE specifies the total size of all files that can be stored in the Flash Recovery Area. This value must be set first. It is NOT the actual size available, but the space which Oracle will use to limit the space of files in the Flash Recovery Area.

DB_RECOVERY_FILE_DEST specifies the physical disk location where the Flash Recovery Area will be stored. The Flash Recovery Area can be stored on a regular file system or can be an ASM group. As the files in the FRA are members of the redundancy set ( backups, archived redo logs and flashback logs), they should be stored in a separate physical location from the database operating components (data files, online redo).

Enable the Flash Recovery Area

To enable the Flash Recovery Area, either restart the database with the related parameters set, or issue the following statements:

ALTER SYSTEM SET db_recovery_file_dest_size = ‘1G’ SCOPE=BOTH SID=’*’;

ALTER SYSTEM SET db_recovery_file_dest=’/u06/bkup/flash_recovery_area’;

ALTER SYSTEM SET db_flashback_retention_target=1440;