Backup of Large Oracle Databases

Use

This section gives you advice on backing up large Oracle databases. Large databases contain 500 GB – 5 TB or more data. For reasons such as the following, you might not be able to back up the database as often as you want to (that is, daily in most cases):

?      Performance problems

There is a heavy load on database server resources, particularly CPU time, system and I/O buses, disk and volume controllers. Therefore, online operations in the SAP System are restricted.

?      Lack of time

Although you normally perform backups at times of low system load, such as at night, you might still find that you exceed the 12 hours available.

?      Data volume

The amount of database data is too great to back up in the time available.

?      Common backup strategy

A common backup strategy for database and non-database files is not a solution since non-database data can better be backed up with operating system tools (such as tar).

Prerequisites

Your system is normally configured so that there is a single server for the database, where no other large applications run.

It is often not recommended to back up large databases across a network because of instability and performance problems.

Features

Whether you can back up large databases with BRBACKUP (and cpio or dd for the copy processes) depends on the following factors:

?      Capacity and maximum throughput of the tape devices

?      Disk access times

?      Maximum throughput of the I/O buses

?      Maximum throughput of the system bus

?      cpio and dd performance, determined by internal buffering and blocking. In general, dd offers much better performance than cpio

BRBACKUP itself places minimal load on the backup process. Any hardware-specific restrictions can only be improved by the hardware vendor.

The hardware configuration for a large database needs careful planning for an optimal backup. This might require multiple tape changes and the management of hundreds of volumes. If possible, use tape jukeboxes or robots supported by the BACKINT interface and external backup programs.

You can reduce the amount of data significantly by using the following features:

?      Incremental backup, which we recommend

?      Standby Database

?      Split Mirror Backup