Tolun ARDAHANLI wrote: > Hi; > > How can I upgrade my Centos from 4 to 5.1? make full backups of all your system volumes (/, /var, and so forth if you have them as seperate volumes), shutdown and boot the CentOS 5.x CD, run an upgrade. this will probably work if your system is quite stock and you've not installed any non-centos4 stuff on it. if you've got a mess of stuff from non-RPM sources and/or nonstandard repositories, chances are you''ll either spend about 60 hours picking through the pieces trying to get it all sorted out, or you'll end up restoring your backups. Personally, I recommend clean installs. backup your user stuff, config files, etc, then wipe and rebuild the system scratch, referring to the previous configs and stuff for reference. YMMV.