First off I'm using the MCE Technologies opti-bay kit so I don't know if that will have a difference or not but I've read that sometimes the cheaper kits will not put the hard drive to sleep properly. Use Cocktail and set your settings: I have my hard drives to spin down after 1 min of inactivity (default is 10 min). Your primary hard drive that your OS is installed on will not go into sleep mode after just 1 min (correct me if you've found otherwise please). My opti-bay hard drive is labeled 'movies' as the only thing I keep on it is.. movies.. so I don't want it spinning all the time even when I'm not using it. You must disable spotlight indexing as shown in the screenshot above to keep spotlight from accessing it every 5 min or so to index the files. If you don't do this then your opti-bay hard drive will continue to spin-up for spotlight to index. You can still search the files it will just be slower.. not noticeable at all IMO since all I have is movie files so it's just looking for one name and not through a bunch of system files. If you disable indexing from your spotlight settings in 'system preferences' (privacy tab) then the indexing AND Finder will be disabled.. so you won't be able to search at all. If you disable indexing in this Cocktail app then it will still let you search files on the drive it just won't let spotlight access it and spin the drive up to index them. Please let me know if this was helpful, I've been trying to fix this problem for a day or so and anything I googled was all the same not-really working kind of stuff..