fedora 20 to 21

Hello, I wish to update a fedora 20 installation to 21 by using a DVD. Is it possible? Actually, I burn a DVD bootable server fedora 21, but I did not find the option update. When I go to installation then System, I can select my hard drive and manually partitioning I can see the installed system (/ /boot and swap) I can install fedora 21 but not on the same partition (I can reuse /boot) I have to install it on a new / I cannot have a mounting point / on the old fedora / This seems to indicate that I cannot upgrade from this DVD. How do you update a fedora 20 without network? Thank. =========================================================================== Patrick DUPRÉ | | email: pdupre(a)gmx.com Laboratoire de Physico-Chimie de l'Atmosphère | | Université du Littoral-Côte d'Opale | | Tel. (33)-(0)3 28 23 76 12 | | Fax: 03 28 65 82 44 189A, avenue Maurice Schumann | | 59140 Dunkerque, France ===========================================================================