Sidebar: Definitions

Data Files -- The physical files that hold the data or indexes. These may be files in a filesystem (e.g., ~/data.dbf) or raw partitions (e.g., /dev/rdsk/c1t0d0s0).

Tablespace -- A collection of data files (e.g., tablespace TBS1 contains files ~/data1.dbf and ~/data2.dbf).

Instance -- Each occurrence, or "instance," of Oracle. This is sometimes referred to as the database, but it can actually contain several databases. There may be one or many instances on each UNIX server, and all will be listed in Oracle's oratab file.

Oratab -- Oracle's global configuration file, listing each instance name, its working directory, and whether it is to be restarted after a reboot.

Redo Log File -- This is a transaction log that keeps track of all changes to each tablespace. It is used to redo those changes during a restore, thus the name. (Each instance has its own set of logs.)

Control File Each instance has a control file that keeps track of all the tablespaces, data files, redo log files, and their current state.