Query the V$DATAFILE view. For example:

SQL> SELECT NAME FROM V$DATAFILE;

::::::::::::

/dev/raw/raw100

/u01/app/oracle/product/10.1.0/dbs/UNNAMED00007

ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT=MANUAL;

ALTER DATABASE CREATE DATAFILE ‘/u01/app/oracle/product/10.1.0/dbs/UNNAMED00007’

AS ‘/dev/raw/raw101’;

ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT=AUTO;

RECOVER MANAGED STANDBY DATABASE DISCONNECT;

Recovery should continue.