Flash recovery area simplifies the ongoing administration of your database by automatically naming recovery-related files, retaining them as long as they are needed for restore and recovery activities, and deleting them when they are no longer needed to restore your database and space is needed for some other backup and recovery-related purpose.
To see up flash recovery follow below steps.
1)Set up DB_RECOVERY_FILE_DEST_SIZE:
SQL> alter system set db_recovery_file_dest_size=2G;
2)Decide the area from OS where you will place Flash recovery area.
SQL>host mkdir /oradata1/flash_recovery_area
3)Set up DB_RECOVERY_FILE_DEST:
SQL> alter system set db_recovery_file_dest='/oradata1/flash_recovery_area';
The V$RECOVERY_FILE_DEST and V$FLASH_RECOVERY_AREA_USAGE views can help to find out the current location, disk quota, space in use, space reclaimable by deleting files,total number of files, the percentage of the total disk quota used by different types of files, and how much space for each type of file can be reclaimed by deleting files that are obsolete, redundant, or already backed up to tape.
In order to disable flash recovery area issue,
SQL> ALTER SYSTEM SET DB_RECOVERY_FILE_DEST='' SCOPE=BOTH SID='*';
Set up Flash Recovery Area for RMAN
Database Startup fails with error ORA-16038,ORA-19809, ORA-00312