Oracle strongly recommends that you back up your database before you upgrade. If errors occur during the upgrade, then you may need to restore the database from the backup.
Use this page to specify whether Database Upgrade Assistant (DBUA) should back up your database for you. If you choose not to use DBUA for your backup, then Oracle assumes that you have already backed up your database using your own backup procedures.
If you use DBUA to back up your database, then DBUA copies all of your database files in the directory that you specify in the Backup Directory field. DBUA performs this cold backup automatically after it shuts down the database and before it begins performing the upgrade. The cold backup will not compress your database files and the backup directory must be a valid file system path. You cannot specify a raw device for the cold backup files.
In addition, DBUA creates a batch file in the directory that you specified. You can use this batch file to restore the database files:
On Microsoft Windows systems, the file is called <SID>restore.bat
On UNIX and Linux systems, the file is called <SID>restore.sh
Overview of the Database Upgrade Assistant
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