“For best results, your external hard drive, thumb drive, SDHC or SDXC card, or other storage device should be formatted as Mac OS Extended, not FAT, ExFAT, or NTFS,” Sellers writes. “And to function as a startup disk, it needs to be using a GUID partition map.”
Sellers writes, “The installer needs at least 8GB of available storage space.”
Read more in the full article here.
MacDailyNews Take: Creating an external Mac startup disk is simple and it’s the best way to mess around with macOS betas when you don’t have a dedicated test Mac at hand.