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After completing the latest update to OS X El Capitan i’ve noticed that i can not see my 2TB hard drive that i had been previously using after removing the super drive and replacing it with said 2TB hard drive over 3 years ago, Am i missing something here???? Any assistance would be greatly appreciated.
This happens occasionally when the computer is updated to a new firmware or OS. Check your SATA cables connected to the hard drive make sure they’re pushed in and secured. If this does not solve it, update your computer to the newest operating system (Mojave as of December 2018) and see what happens there. I have the same model Macbook Pro as you and I am currently running an SSD and a HDD with no issue.
