A predefined role, named "DBA", is automatically created with every Oracle database. This role contains all database system privileges. Therefore, it is very powerful and should be granted only to fully functional database administrators.
Two user accounts are automatically created with the database and granted the DBA role: SYS – CHANGE_ON_INSTALL and SYSTEM – MANAGER.
The database administrator usernames need a more secure authentication scheme.
Network administrators – responsible for administering Oracle networking products, such as Net8.
Data files – Every Oracle database has one or more physical datafiles . One or more datafiles form a logical unit of database storage called a tablespace.
Redo log files – Every Oracle database has a set of two or more redo log files . The set of redo log files for a database is collectively known as the database's redo log .
Control files – Every Oracle database has a control file . A control file contains entries that specify the physical structure of the database such as database name, names and locations of the data files and redo log files, time stamp of database creation, etc.
The process of periodically taking a copy of the database and log file (and possibly programs) onto offline storage media.
A DBMS should provide logging facilities referred to as journaling, which keep track of the current state of transactions and database changes, to provide support for recovery procedures.
A DBMS should provide a checkpoint facility, which enables updates to the database which are in progress to be made permanent. When a checkpoint is taken, the DBMS ensures that all the data in main memory is written out to disk and a special checkpoint record is written to the journal.
A backup is a copy of data. You can make physical backups using either the Oracle8 i Recovery Manager utility (http://technet.oracle.com/doc/oracle8i_816/server.816/a76990/toc.htm) or operating system utilities (http://technet.oracle.com/doc/oracle8i_816/server.816/a76993/osbackup.htm#7605).
A physical backup is a copy of a datafile, tablespace, or database made at a specific time.
To restore a physical backup is to reconstruct it and make it available to the Oracle database server.
To recover a restored datafile is to update it using redo records , that is, records of changes made to the database after the backup was taken.
Oracle performs crash recovery and instance recovery automatically after an instance failure. Instance recovery is an automatic procedure that involves two distinct operations: rolling forward the backup to a more current time by applying online redo records and rolling back all changes made in uncommitted transactions to their original state.
Media recovery requires you to issue recovery commands.
Static Data Dictionary Views - change only when a change is made to the data dictionary, for example, when a new table is created or a user is granted new privileges. (http://technet.oracle.com/doc/oracle8i_816/server.816/a76961/ch2.htm)
Oracle contains a set of underlying views that are maintained by the server and accessible to the database administrator user SYS. These views are called dynamic performance views because they are continuously updated while a database is open and in use, and their contents relate primarily to performance. (http://technet.oracle.com/doc/oracle8i_816/server.816/a76961/ch3.htm)