I want to build a proper server with room for 40+ HDDs to move my media server to and have RAID 1. I know a lot about PCs and software, but when it comes to server hardware I have no clue what I'm doing. How would I go about building a server that has access to 40+ RAID 1'd HDDs?
It is far less improbable than you think, especially if all of your drives have similar age/wear - as would be the case if you bought all 40 around the same time.