A database administrator's responsibilities can include the following tasks:
1、Installing and upgrading the Oracle Database server and application tools
2、Allocating system storage and planning future storage requirements for the database system
3、Creating primary database storage structures (tablespaces) after application developers have designed an application
4、Creating primary objects (tables, views, indexes) once application developers have designed an application
5、Modifying the database structure, as necessary, from information given by application developers
6、Enrolling users and maintaining system security
7、Ensuring compliance with Oracle license agreements
8、Controlling and monitoring user access to the database
9、Monitoring and optimizing the performance of the database
10、Planning for backup and recovery of database information
11、Maintaining archived data on tape
12、Backing up and restoring the database
13、Contacting Oracle for technical support

Task 1: Evaluate the Database Server Hardware
How many disk drives are available to the Oracle products
How many, if any, dedicated tape drives are available to Oracle products
How much memory is available to the instances of Oracle Database you will run (see your system configuration documentation)

Task 2: Install the Oracle Database Software
The logical storage structure of the database
The overall database design
A backup strategy for the database
affect:
The performance of the computer executing running Oracle Database
The performance of the database during data access operations
The efficiency of backup and recovery procedures for the database

Task 3: Plan the Database
You have multiple production database systems.
You want to create development and test systems that are identical to your production system.
Cloning an Oracle home—Just the configured and patched binaries from the Oracle home directory and subdirectories are copied to the destination host and "fixed" to match the new environment. You can then start an instance with this cloned home and create a database.
Cloning a database—The tuned database, including database files, initialization parameters, and so on, are cloned to an existing Oracle home (possibly a cloned home).

Task 4: Create and Open the Database
Task 5: Back Up the Database
Task 6: Enroll System Users
Task 7: Implement the Database Design
Task 8: Back Up the Fully Functional Database
Task 9: Tune Database Performance
Task 10: Download and Install Patches
Task 11: Roll Out to Additional Hosts