Is it possible ? If I try a fresh install, it means I have to disconnect server, backup everything, install new OS, then install virtualmin and restore everything from backup ... (should it work backup restore if it's from centos 4 to centos 5 ?) You understand it will be very long ... I was searching if it was possible to upgrade os version (like in ubuntu) but wasn't able to find an answer.
Upgrading CentOS 4.8 (final) to 5.x