In my general DSM7 article you can feel how excited I was about the new version of DSM. Still, going with the new version of any OS on your production device is no small feat. Is jump to DSM7 justified? Is this something that you should do? Can you go back? Let's see.
First question. Do you have a valid backup of your data? No? Shame on you! Do it and then come back. Yes? Nice one, you can proceed.
Like with any version of DSM upgrade to DSM7, at the moment, will require you to download the specific version for your NAS and install it manually using the Control Panel > Update and Restore section.
There you will see a Manual DSM update button. Use it to initiate an upload of your DSM7 install and then the installation itself.