> Well that 24/7 db server is not going to back up itself and maintain itself when the HW fails or the power goes out.

Uh, yeah, that's why you pay IT people to do that sort of thing. Hiring your own will almost certainly be less expensive than paying Amazon's people, and provides you more control and more options in the event of any problems. It's not like AWS never has problems, and when it does all you can do is twiddle your thumbs until someone else fixes it.