I have installed ubuntu-server 11.10 in virtual box. but unfortunately the screen is small. I installed VirtualBox guest additions to see it full screen(like what I do for windows). Now it is installed and its services are running but I still don't get full screen. There is not GUI. I just installed xorg. Could anyone help?
VirtualBox Guest Additions are works for graphical interface, not for text interface...
If you set console frame buffer in grub conf you might have full screen virtual ubuntu server. Take a look at this link for more information..
IMO connecting with ssh to virtual machine is safer than changing frame buffer settings in grub. You can change ssh window height & width as you wish. And nothing is different with real terminal.
I might try the
Next, go to Start –> All Programs –> Accessories –> Remote Desktop Connection from your Windows computer and type the IP address or Hostname of the Ubuntu machine then click ‘Connect’
And, use your Ubuntu username and password.
on VirtualBox menu - "Devices > Enable remote desktop display"
You can have the ubuntu server console in VirtualBox start at a resolution that your graphic card supports via the virtualbox environment.
Quick Steps (Source)
You should now see your VM's console in the custom resolution that you just set.
(PS: As Javier Rivera said, full screen resolution may not be possible.)