I know this is an older post and not meaning to necro-post but I am using an old computer case for my Unraid and I purchased a hot swap cage that holds 5 drives and fits into a 3x 5.25" bay. I do recommend it but also mine is housing 5 14tb drives and with parity being ran they do get into 50c range. I plan on swapping 3 out for SSDs for better air flow and moving them (3 HDDs) to different location once I get this case in this thread.
https://www.icydock.com/goods.php?id=155
I also replaced the included fan with a Noctua one that is quieter/better.
