ORA-02065: illegal option for ALTER SYSTEM

Question

I'm new to Oracle. I was learning Backup and Recovery. For that, I did

$ sqlplus system/password

SQL> alter system set db_recovery_file_dest_size=8gb scope=both;

But I got error this error:- enter image description here

Can anyone tell me the exact solution? Please do tell me the specific solution with all the steps to do.

Answer 1

$ sqlplus system/password

SQL> alter system set db_recovery_file_dest_size = 8g scope = both;