I Googled the title of your post... you should try it. 😉
We don't use AG at work and so I've not actually used it. If I were put on the spot to do something like you ask, I'd Google for the info and read the documentation. In my Google search, I found the following article. I've not studied it nor even completely read it but, from the little I did read, the author seems pretty savvy.
I'll also suggest that "NO DOWNTIME" is wishful thinking but you can help minimize it.