I've got a Mac Pro 4,1 "Cheese Grater" with multiple internal drives. I've got 10.6.8 Snow Leopard on drive #1 (this is my primary OS for this older Mac, and I will continue to use that). I also have 10.10.5 Yosemite on drive #2. Drive #3 is empty and ready for installation of 10.11 El Capitan. The machine should be eligible for 10.11. I have the link to download it from the App Store (thank you to Kurt Lang for posting that link).
My question: I assume that I can point the El Capitan installation to target Drive #3, and it won't mess with the content and boot systems on Drive #1 and Drive #2 at all - right? My goal is to end up with all three OSes, one on each drive, and retain my ability to boot off any of the three. The target disk for the installation should be obvious during the installation process - right? I will be booting off Drive #2 running 10.10.5 Yosemite (unless there's a reason to boot off Snow Leopard...).
Any gotchas I need to watch for in this process?
Thanks for the help/re-assurances!
