Is there a minimum size disk required to be recognized when an option key is pressed on start? What are the requirements for the option boot device? I realize this is a fine point.
Mac mini 2018 or later
MacOS Base System (the ROM resident system used for Internet recovery) is only about 2GB in size.
MacOS EFI -- the stand-alone booter and sometimes firmware updater has to fit inside a 209.7 MB partition on the drive.
This discussion could be FAR more interesting and enlightening (and likely more useful) if you would divulge where you are going with this.
Why are you asking this?
If the OS will install and run, that's all you need technically. The smallest I've ever seen apple use was in the 120 GB range.
Per Disk Utility, my Macintosh HD takes up 15.19 GB. So I'd say 15.19 GB in minimum.
However, to actually install the OS requires more space initially. Exactly how much, I dunno. Maybe 20 GB or so more.
Is there a minimum size disk required to be recognized when an option key is pressed on start? What are the requirements for the option boot device? I realize this is a fine point.
