Backing Up Oracle - Computing at Cornell
Backing Up Oracle - Computing at Cornell
Backing Up Oracle - Computing at Cornell
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For each type of event th<strong>at</strong> may occur, designers of a d<strong>at</strong>abase backup and<br />
recovery solution must:<br />
Ensure th<strong>at</strong> oper<strong>at</strong>ional procedures specify who needs to do wh<strong>at</strong>, in order<br />
to recover from loss or corruption of d<strong>at</strong>a used by the RDBMS.<br />
Ensure th<strong>at</strong> the d<strong>at</strong>a files th<strong>at</strong> the RDBMS recovery routines use are<br />
available when needed.<br />
Ensure th<strong>at</strong> any d<strong>at</strong>a which the RDBMS does not manage can be<br />
recovered to a st<strong>at</strong>e th<strong>at</strong> is consistent with the d<strong>at</strong>abase.<br />
3.1.2 Speed of recovery<br />
If you ask users how quickly they would like you to be able to recover lost<br />
d<strong>at</strong>a, they usually answer "immedi<strong>at</strong>ely". In practice, however, recovery takes<br />
time. The actual time taken depends on a number of factors, some of which<br />
are outside your control (for example, hardware may need to be repaired or<br />
replaced). Nevertheless, there are certain things th<strong>at</strong> you can control and th<strong>at</strong><br />
will help to ensure th<strong>at</strong> recovery time is acceptable:<br />
Develop a str<strong>at</strong>egy th<strong>at</strong> strikes the right balance between the cost of<br />
backup and the speed of recovery.<br />
Document the procedures necessary to recover from the loss of different<br />
groups or types of d<strong>at</strong>a files.<br />
Estim<strong>at</strong>e the time required to execute these procedures (and do not forget<br />
the time involved in identifying the problem and the solution).<br />
Set user expect<strong>at</strong>ions realistically, for example, by publishing service<br />
levels th<strong>at</strong> you are confident you can achieve.<br />
3.1.3 Backup windows<br />
Some RDBMSs do not allow d<strong>at</strong>abases to be backed up while they are in<br />
use. In such cases, you need to shut down the d<strong>at</strong>abase before the backup<br />
starts, and you cannot restart the d<strong>at</strong>abase until after the backup has<br />
completed.<br />
Shutting down a d<strong>at</strong>abase often means th<strong>at</strong> users cannot use applic<strong>at</strong>ions.<br />
You need to ensure th<strong>at</strong> the times <strong>at</strong> which d<strong>at</strong>abases are shut down and<br />
unavailable are acceptable to your users.<br />
Even if you can perform backups while the d<strong>at</strong>abase is oper<strong>at</strong>ional, you need<br />
to ensure th<strong>at</strong> any load on processors or networks caused by the backup<br />
process does not result in performance or responses th<strong>at</strong> are unacceptable to<br />
your users.<br />
24 <strong>Backing</strong> <strong>Up</strong> <strong>Oracle</strong> using Tivoli Storage Management
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