Explaining how to move datafile from one ASM DG to another.
Note: Database must be in archivelog mode before doing this activity.
1. Find the name of the datafile that you're going to migrate
SQL> SELECT file_name FROM dba_data_files;
FILE_NAME
----------------------------------------------
+DATA/mydb/datafile/system.312.825938943
+DATA/mydb/datafile/sysaux.313.825938957
+DATA/mydb/datafile/undotbs1.314.825938971
+DATA/mydb/datafile/undotbs2.315.825938991
+DATA/mydb/datafile/users.317.825939005
+DATA/mydb/datafile/mydb01.dbf
+RECO/mydb/datafile/mydb_tbs.7665.836338453 <Moving this file from +RECO to +DATA
7 rows selected.
2. Take the datafile offline
SQL> Alter database datafile '+RECO/mydb/datafile/mydb_tbs.7665.836338453' offline;
Database altered.
3. Copy the file using RMAN: