I want to create an emergency startup system on a ZIP Drive. How large does the drive need to be for High Sierra, 10.13.4. I do not plan to use it for any additional storage.
MacBook Pro TouchBar and Touch ID, macOS High Sierra (10.13.3)
I think you will find that the existing Recovery Partition covers these eventualities:
https://support.apple.com/en-us/HT201314
You may wish to keep a full installer on a USB drive or an external clone, for more intensive erase/reformat of your system. The clone also gives you an extra bootable external backup of your data.
https://support.apple.com/en-us/HT201372
Then there is the basic backup system that everybody should maintain, with Time Machine:
Time Machine might be the best thing ever made for computers ...THANK YOU
Emergency Startup Drive...
