RMAN Backup (when db is online)

1) Check the ORACLE_SID. The target database will be the value stored in it.

2) Make sure that the database is in archive_log mode
select log_mode from v$database;

3) Add these parameters in init.ora file
db_recovery_file_dest=/.../.../flash_recovery_area
db_recovery_file_dest_size= 2147483648

4) startup pfile =

5) > rman target / nocatalog

6) RMAN> backup database plus archivelog;