V$BACKUP

V$BACKUP displays the backup status of all online datafiles.

Column	Datatype	Description
FILE#	NUMBER	File identifier
STATUS	VARCHAR2(18)	File status: NOT ACTIVE, ACTIVE (backup in progress), OFFLINE NORMAL, or description of an error. NOT ACTIVE indicates that the file is not currently in backup mode (that is, an ALTER TABLESPACE ... BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP statement has not been issued), whereas ACTIVE indicates that the file is currently in backup mode.
CHANGE#	NUMBER	System change number when backup started
TIME	DATE	Time the backup started

Note:

1.

select d.name, b.* from v$backup b, v$datafile d where b.file#=d.file#;

NAME	FILE#	STATUS	CHANGE#	TIME
/oracle_data/mydb/system01.dbf	1	NOT ACTIVE	2210368887096	2005-09-14 12:48:57 PM
/oracle_data/mydb/undo25.dbf	2	NOT ACTIVE	0	NULL
/oracle_data/mydb/sde_logfile.dbf	3	NOT ACTIVE	0	NULL
/oracle_data/mydb/tools01.dbf	7	NOT ACTIVE	2210369026684	2005-09-14 2:41:08 PM
/oracle_data/mydb/users01.dbf	8	NOT ACTIVE	2210369651966	2005-09-14 7:25:53 PM

Oracle data dictionary views

Oracle dynamic performance views