How to add data files in Oracle ASM?

To add data files to Oracle ASM, you can follow these steps:

1. Connect to the database using SQL*Plus or any client tool that supports Oracle databases.
2. Ensure you have the necessary permissions to carry out this operation. You need to have SYSDBA or SYSASM privileges.
3. Login to the ASM instance using the SYSASM identity at the SQL*Plus command prompt. The command is similar to:
4. Connect to the Oracle database as the SYSASM user using SQL*Plus.
5. Create a new ASM disk group (if it does not already exist). You can create a new disk group using the CREATE DISKGROUP statement. For example:
6. Establish a disk group named mydata with normal redundancy, including failgroups disk1 and disk2 each containing a 10G disk.
7. In this example, a disk group named mydata is created with normal redundancy. The disk group consists of two failure groups, each containing one disk.
8. Add data files to the disk group. You can use the ALTER TABLESPACE statement to add data files to the ASM disk group. For example:
9. Add a 1GB data file to the mytablespace tablespace named +mydata.
10. In this example, adding a 1G data file to the tablespace named mytablespace.
11. Please note that in the ALTER TABLESPACE statement, we use the name of the ASM disk group (starting with a plus sign) instead of the actual file path.
12. You can verify if a data file has been successfully added to an ASM disk group using the SELECT statement on the V$ASM_FILE view. For example:
13. Retrieve the file number, filename, and tablespace name from the V$ASM_FILE view.
14. This query will retrieve the file number, file name, and tablespace name for all files in the ASM disk group.

In this way, you have successfully added a data file to Oracle ASM.