How to move a datafile from one ASM disk group to another

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:

RMAN> COPY datafile '+RECO/mydb/datafile/mydb_tbs.7665.836338453' to '+DATA';

Starting backup at 18-FEB-14

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=493 instance=mydb device type=DISK

channel ORA_DISK_1: starting datafile copy

input datafile file number=00012 name=+RECO/mydb/datafile/mydb_tbs.7665.836338453

output file name=+DATA/mydb/datafile/mydb_tbs.385.839852436 tag=TAG20140218T122054 RECID=5 STAMP=839852676

channel ORA_DISK_1: datafile copy complete, elapsed time: 00:03:45

Finished backup at 18-FEB-14

4. Change datafile's name to the new name to update data dictionary 

SQL> Alter database rename file '+RECO/mydb/datafile/mydb_tbs.7665.836338453' to '+DATA/mydb/datafile/mydb_tbs.385.839852436';

Database altered.

5. Rename the datafile using RMAN to update ASM. This command is equivalent of "alter database rename file":   

RMAN> SWITCH DATAFILE '+DATA/mydb/datafile/mydb_tbs.385.839852436' to copy;

using target database control file instead of recovery catalog

datafile 12 switched to datafile copy "+DATA/mydb/datafile/mydb_tbs.385.839852436"

6. Recover  the new datafile:

RMAN> RECOVER DATAFILE '+DATA/mydb/datafile/mydb_tbs.385.839852436';

Media recovery complete.

7. Bring it online

SQL> ALTER DATABASE DATAFILE '+DATA/mydb/datafile/mydb_tbs.385.839852436' ONLINE;
Database altered.

8. Now check datafile name

SQL> SELECT file_name FROM dba_data_files;

FILE_NAME

----------------------------------------------

+DATA/mydb/datafile/system.314.825938943

+DATA/mydb/datafile/sysaux.315.825938957

+DATA/mydb/datafile/undotbs1.316.825938971

+DATA/mydb/datafile/undotbs2.318.825938991

+DATA/mydb/datafile/users.319.825939005

+DATA/mydb/datafile/mydb01.dbf

+DATA/mydb/datafile/mydb_tbs.385.839852436  <<<< Datafile Name Changed in new DG

7 rows selected.