I've just completed the install procedure for two, 2TB hard drives in my mid-2011 Mac Mini server. The server had been 'downgraded' to just run regular Mac OS Sierra on one 750 GB drive, with the second 750GB drive for data. Both drives in the machine were backed up to a single, 2TB external drive using Time Machine.

I created a bootable install disk for Sierra and booted from there once the new drives were installed. Pulled up disk utility, but it was only seeing one of the two new drives. So, my first question is:

  1. Should the computer have seen both drives, or only the drive in whatever the '1st slot' would be?

Also, I've just started a restore process from disk utility. I was already in that tool to format the drive that it could see, so I just went ahead and hit restore from the Time Machine backup to the drive I formatted as Mac OS Extended (Journaled). Second and third questions are:

  1. Should I have actually used time machine instead? (restore is in progress, can't seem to cancel) What's the difference?

  2. Would it have been better to install Sierra and then restore from time machine?

The restore from Disk Utility seems to be doing it's thing..(says it's restoring)

1 Answer 1


To answer your questions as numbered:

  1. Yes the computer should have seen both drives. Have you checked to make sure the drives are properly seated and the SATA cable plugged in properly?

  2. I would always suggest doing a clean install of the OS and using Migration Assistant instead of Time Machine (you can do a Migration from a Time Machine backup) because anything that's currently associated with the UUID or anything else specific to the old HDDs may be weird when it recognizes the new drives as being different. Migration assistant fixes these problems and makes sure any app licenses transfer properly.

  3. As I stated in my answer number 2, I would argue yes, with some changes.

If I were you, I would take the following steps:

  1. I would try to figure out why my second HDD wasn't showing up. If necessary, I'd take the computer apart and replug its SATA cable.

  2. Once I had both HDDs working, I'd format both of them to their final formats (likely HFS+).

  3. I'd do a clean install of MacOS Sierra.

  4. After setting up the computer, I would use spotlight to open the Migration Assistant app and migrate from that time machine backup.

  5. Once the migration was complete, I would make time machine back up all of the data. This way, all of the new, migrated information has a backup.

  • 1
    Thanks Noah! I did some troubleshooting this morning. After identifying which drive was not working with a tech at OWC, I've since removed that drive and am now proceeding with the clean install on the working drive and then restoring files using migration assistant as you've suggested. I moved the working drive from the lower to the upper bay and removed the drive that wasn't working. The next step is to test the drive externally. If I still can't get it to mount, it's very likely just DOA hardware.
    – Brent
    Jan 14, 2017 at 18:02
  • @Brent good luck!
    – NoahL
    Jan 14, 2017 at 19:21

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