I read many documents-articles-posts so I can't remember everything, but I think I read somewhere that it is possible to install the new updates of osx in external hard disk with bootable image of the whole environment of osx? Is this true? If this is valid, how can I do it? I mean, maybe I can choose the external hard disk for installation, but in normal installation in internal hard disk, it reboots, it continues installation etc. Can you please clarify me if this can be done and how it should be done?