Understanding Oracle Backup & Recovery

W. Curtis Preston

This month's article will explain the elements of Oracle architecture that make backup and recovery possible. Understanding these architectural elements is key to being able to successfully backup and recover Oracle.

Historically, Oracle did not have a standalone backup utility like Informix's ontape or Sybase's dump, opting instead for commands that allow the DBA to use any backup utility. Oracle7 introduced the EBU, or Enterprise Backup Utility, but it is designed to work only with other commercial backup utilities. (Oracle8 now comes bundled with an OEM version of Legato Networker, which means that you do have another free option now, but this setup is still not as easy to use as ontape or dump.) Oracle8 introduced the Recovery Manager (rman), which also is designed to work with commercial backup utilities and added a lot more functionality.

Environments without a commercial utility must use backup scripts of some kind. This method is certainly the least user-friendly and most difficult to learn if you are new to Oracle and scripting, but also allows for the greatest flexibility during both backup and restore. This complexity, of course, requires a bit more explanation.

This article will use the Oracle8 command svrmgr for interfacing with Oracle databases. If you are running Oracle7, the command is sqldba.

Oracle Architecture

It is important to understand the design of the database that is being backed up. We will start with the power user's view of the database, and then continue with that of the database administrator.