Chosen Solution
Hello, So I just installed two new hard drives into my macbook pro. The samsung 850 evo 500gb and a HGST Travelstar 1tb. The SSD is in the original spot where my old hard drive was and is functioning properly. Where I am having issues is trying to format the HDD in the optical bay slot. When I try to format the drive it fails and I have tried this several times! If you need any details the HGST Travelstar is 2.5 inch 1tb 5400rpm SATA 6gb/s 8MB Cache
Put the HGST Travelstar in the original bay and see if you can work with it.
I found cheap CD bay drives can’t by used like normal. Format it using a proper USB HDD caddy then reincert it in your machine. I would recommend using it as extra storage not a second o.s
I had a similar experience when using a cheap caddy. Then I ordered something called OptiBay and now my drive formats/ repairs correctly. I’m not promoting the product but it just works. EDIT: Sorry to dig out this old thread but I was facing this issue and was following this topic since then. Once I resolved my issue I decided to post it here so that it can help someone who’s wasting their time with this problem.
