disk full message when installing

Hello, As a test I try to install Crux on a VMWare.So I made a 8G disk and formatted it with btrfs.Then I start up the installer and all the packages installed fine( Core, Xorg and Contrib).So far no problem. Then I try to change the contents of /etc/rc.conf as described in the manual.As soon as I try to save it, I get a disk full message. Is 8G to little for a install or is there something else wrong ? Roelof