Backing Up Oracle - Computing at Cornell

Table A Table B
Tablespace 1
data file or
directories
on file
systems
Figure 3. Tables, tablespaces, and data storage
Tablespaces are simply logical concepts utilized by RDBMSs. They provide a
convenient way of separating the user's view of data from some of the
practical considerations associated with storing that data on disk. For
example, a database administrator can make more disk space available to
several tables by adding disk space to the appropriate tablespace, thus
ensuring that tables do not run out of space and that disk space is used
efficiently. Furthermore, the tablespace concept means that neither users nor
application programs need to be aware of the fact that the database
administrator has made more disk space available.
Data storage in tablespaces can be implemented using either data files or
directories on files systems or raw devices. (For information on file systems
and raw devices, please see your operating system documentation.)
Tablespaces provides the link between logical views and data storage. Here
are some points to note:
The data for a table or index may be contained in only one data storage.
Alternatively, the data for a table or index may be spread over several data
storage.
Each of the data storage may contain data for one or more tables in the
tablespace.
Each data file or directory may reside in a separate file system.
The significance of these alternatives is that the only way to back up or
recover individual tables is by using the facilities that the RDBMS provides.
12 Backing Up Oracle using Tivoli Storage Management
Index B
Tablespace 2
raw devices raw devices
Data Storage (Disks)
System
Tables
System
Tablespace
data file or
directories
on file
systems