Output v$flash_recovery_area_usage is incorrect

sometimes we clean recovery area manually , delete archive logs, old files ourselves
the output v$flash_recovery_area_usage can be  incorrect.

Use rman to sync the data dictionary

RMAN>CROSSCHECK BACKUP;
RMAN>CROSSCHECK ARCHIVELOG ALL;   (crosscheck won't delete, just mark them)

RMAN>Delete expired backup;     (will delete items which crosscheck fail )
RMAN>Delete expired archivelog all;
RMAN>Delete force obsolete;

RMAN> list backup    (it won't list data copies )
RMAN> list datafilecopy all;
RMAN> crosscheck datafilecopy all;
RMAN> delete datafilecopy all;
RMAN>delete datafilecopy tag=test_copy;

RMAN>Delete archivelog all completed before  'SYSDATE-7';
 
Then
use exec dbms_backup_restore.refreshagedfiles ; 
to refresh