PreUpgrade
PreUpgrade is an application users run on an existing Fedora 7 or above installation, that resolves and downloads packages required to upgrade Fedora. While PreUpgrade downloads the necessary packages, users are free to continue using their systems.
To use PreUpgrade to upgrade to a newer Fedora release:
1. Back up all important data before upgrading.
1. Run the yum update command as root to make sure all packages are updated to their latest versions.
1. Run the yum install preupgrade command as root to install PreUpgrade.
1. Run the preupgrade command as root to start the PreUpgrade application.
1. Select the Fedora release you want to upgrade to on the Choose desired release screen, and click the Apply button.
1. When all of the packages have downloaded, reboot your system to start the Fedora 9 installer.
For further information, refer to the PreUpgrade feature page: