Backing Up Oracle - Computing at Cornell
Backing Up Oracle - Computing at Cornell
Backing Up Oracle - Computing at Cornell
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2.2 <strong>Oracle</strong>8i overview<br />
The previous section has provided a generic overview of d<strong>at</strong>abases for<br />
system administr<strong>at</strong>ors responsible for designing a backup and recovery<br />
system for d<strong>at</strong>a held on a rel<strong>at</strong>ional d<strong>at</strong>abase. The purpose of the current<br />
section is to introduce <strong>Oracle</strong> version 8.1.7 concepts th<strong>at</strong> can help system<br />
administr<strong>at</strong>ors or TSM administr<strong>at</strong>ors to implement a backup str<strong>at</strong>egy th<strong>at</strong> is<br />
specific to <strong>Oracle</strong>.<br />
Common concepts like tables and indexes already mentioned in 2.1,<br />
“Fundamentals of Rel<strong>at</strong>ional D<strong>at</strong>abase Management Systems” on page 9 are<br />
no longer mentioned in this section. R<strong>at</strong>her, we concentr<strong>at</strong>e on concepts th<strong>at</strong><br />
are new or specific to <strong>Oracle</strong>.<br />
2.2.1 Instances<br />
An instance, when started, alloc<strong>at</strong>es its own memory called the system global<br />
area (SGA) and starts a set of background processes. The SGA is used for<br />
d<strong>at</strong>abase inform<strong>at</strong>ion th<strong>at</strong> is shared by d<strong>at</strong>abase users. Typically, there is one<br />
instance per d<strong>at</strong>abase. In a parallel environment, the d<strong>at</strong>abase will be shared<br />
by multiple instances. See 2.2.10, “Parallel server option” on page 19 for<br />
more discussion on parallel processing.<br />
2.2.2 D<strong>at</strong>abases<br />
A d<strong>at</strong>abase would consist of one or more logical units called tablespaces. On<br />
the physical layer, the d<strong>at</strong>abase will have d<strong>at</strong>afiles, control files, and<br />
optionally a password file.<br />
2.2.3 Tablespaces<br />
When a d<strong>at</strong>abase is cre<strong>at</strong>ed, a d<strong>at</strong>a dictionary is cre<strong>at</strong>ed in the system<br />
tablespace. Although It is not required to cre<strong>at</strong>e additional tablespace,<br />
additional tablespaces are recommended for user d<strong>at</strong>a. The d<strong>at</strong>a dictionary is<br />
critical to the oper<strong>at</strong>ion of the d<strong>at</strong>abase because it records, verifies, and<br />
conducts ongoing work. The system tablespace is always online and cannot<br />
be taken offline because the d<strong>at</strong>a dictionary must always be available to<br />
<strong>Oracle</strong>. We recommend th<strong>at</strong> you reserve the system tablespace for use by<br />
<strong>Oracle</strong>; do not cre<strong>at</strong>e any user tables in this tablespace.<br />
You must ensure th<strong>at</strong> the system tablespace is backed up successfully every<br />
time you do a d<strong>at</strong>abase backup.<br />
16 <strong>Backing</strong> <strong>Up</strong> <strong>Oracle</strong> using Tivoli Storage Management
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