Some workplaces have multiple database platforms that you will be responsible for. The main thing a DBA is responsible for is being able to recover the database in case of a disaster. Below is an easy way how to backup an Oracle database using RMAN. Is it the only way to do this? Of course not, there a literally dozens of ways depending on how complicated your environment is, but it is a legitimate way to create a backup and it will save you. In the next posting, I will show you how to restore the database onto a new server.
Jim Salasek's SQL Server Blog 