How to reinstall Macintosh HD Data drive

Hi TechieOne,

You were correct to delete the Macintosh HD - Data volume. If you left it behind and installed macOS High Sierra or later, that would have left all of the previous data behind.

To reinstall macOS Sierra, you will need to format (erase) your internal drive as Mac OS Extended (Journaled), since macOS Sierra doesn't support starting up from an APFS container. For context, your previous volumes (Macintosh HD and Macintosh HD - Data) were APFS volumes, inside an APFS Container (partition).

To format your drive as Mac OS Extended (Journaled):

1. Start up in macOS Recovery for macOS Sierra:
   1. If your Mac shipped with macOS Sierra: hold down Shift-Option-Command-R as you power on or restart your Mac. Release the keys when a spinning globe appears. You will need to connect to a Wi-Fi network when prompted.
   2. If your Mac shipped with OS X El Capitan or earlier: You will likely need to create a bootable installer for macOS Sierra using a working Mac. Use the command at the bottom of this reply when needed.
   3. If your Mac shipped with macOS High Sierra or later: Unfortunately, your Mac likely doesn't support macOS Sierra.
2. When the list of utilities appears, select Disk Utility and click Continue.
3. In Disk Utility, select View -> Show All Devices.
4. Select the Apple SSD entry and click Erase. Choose these options, then click Erase:
   1. Name: Macintosh HD
   2. Format: Mac OS Extended (Journaled)
   3. Scheme: GUID Partition Table/Map
5. When the erase is finished, quit Disk Utility and reinstall macOS Sierra.

To create a bootable installer for macOS Sierra, use this command when you reach step 3 in the linked Apple Support article:

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app

Great to hear! Happy new year to you as well :)