A database administrator (short form DBA) is a person responsible for the installation, configuration, upgrade, administration, monitoring and maintenance of databases in an organization. However, each part in itself has so many role and responsibility to play. I am here presenting only general description of each and every task without going in to technical detail. So let's see all one by one.
1. Installation: Database Administration is responsible for installation of Oracle Database Software on Servers. This installation includes making user on OS, installation of OS patches, changing kernel parameter suitable for Oracle version and finally setting up environment variables for smooth working of database.
2. Configuration: Next task is DBA's kitty is to create databases on server having Oracle database software installed. There are two ways of creating database manually or using GUI, approach depends on requirements. After, database creation, it needs to configure or optimize database parameters for better performance.
3. Upgrade: As we know, world is always changing so the technology. Hence, one more task for database administrator to upgrade database from one version to another. Like upgrade from 9i to 10g or 10g to 11g etc. Upgrade is done by keeping in mind, recovery of database in case of upgrade failure and time slot assigned for it, specially when it is production database.
4. Administration: Once your database is up and running, it needs constant maintenance that includes providing enough space for database to grow, removing trace files, creating and resizing datafiles as required. Checking alert log file for any issue and resolving them accordingly.
5. Monitoring: This is another important task for a database administrator, a DBA needs to continuously monitor the DB for any forthcoming or current issues. In case of Oracle, it provides DB Console to monitor Database or DBA can make customized scripts which raise alert in case of abnormal happening. Alert log is the file which log all DB activities and first to look into in case of any issue.
6. Maintenance: Database maintenance mainly includes taking database backups for restoration in case of corruption or loss of datafiles etc. Though, once configured backup jobs really doesn't need anything to do other than monitoring. But, recovering of DB is another major task for a DB. This also covers performance tuning of database also, which another vast area to explore or a DBA. You can find DBA's in marked those who are expert in performance tuning only. There can be plant of reasons for DB to not perform well like bed sql programming, poor server configuration, bed infrastructure.
Though, having so many things to do, DBA's always have respectable and most secure job in any organization. One important thing about being a DBA is, it's very tough to get an entry into this field. Since, no one wants to take risk with their organizations data by giving this to a fresher.