I verified it, ran repair, and choose it as the Startup Disk. The next time I was in disk utility, I could finally see the internal hard drive.
For a new aluminium mac mini you will need to replace one of the internal drives.
Ran Apple Hardware Test (Hold R on startup) This showed a passing ADP000 reference code. For a Macbook or Macbook Pro can replace the internal optical drive with your old Hard Drive or order a large SSD drive and replace your old hard drive with it. On the built in keyboard press left Shift + Control + Option + Power button at the same time. Connect your MagSafe adapter to a power source and then to your Mac. Apple's KB article HT3964 explains this a bit more in detail. 4A drives as the rest of Apple’s product lines, but didn’t support the PCIe 3.0 connection the newer drives were capable of. “ Disk utility also still shows no internal hard drive. A lot of odd issues, not just disappearing hard drives, can be resolved with an SMC reset. Create at least 3 backup copies, store 2 copies in different media, and preserve 1 copy offsite. Disk Utility is a built-in macOS diagnostic tool to eliminate fundamental issues such as directory structure damage, file system permission problem, and so forth. “The 13″ MacBook Air used the same Gen. Back up your Mac external hard drive manually using Command + C and Command + V hotkey. You might have used the Disk Utility functionality of Mac to diagnose and resolve problems encountered in your Mac hard drive. Keep in mind the source partition must be the same or smaller then. The detailed description is in our article Clone your Mac system disk to a new hard drive (SSD).
The blog further commented that for MBA 13” 2015 and MBA 13” 2017, the hardware is PCIe 3.0, but this product line doesn’t support PCIe 3.0 (See “MacBook Air (Early 2015 - Mid 2017)” section): '' Boot to OS X Utilities Open Disk Utility Restore tab As a source set old hard drive in HDD rack and as a destination new installed SSD. The blog written about this classify MBA 20 as “Generation 4”. Seems that both MBA 13” 2015 and MBA 13” 2017 both has 4x PCI-e 3.0