and an 8 GB extra partition (in case I need to make it ExFat or FAT for file transfers.) (I use 12 GB for the installer, 42.1 GB for a “Rescue Drive” with a fully bootable OS, installer, Drive Genius, etc. You could also use a secondary internal partition that has at least 12GB of available disk space for the installation files.

Mount your USB flash drive or other volume.

The installer will be in your Applications folder. Quit the installer if it opens automatically after downloading.

Download the macOS installer from the Mac App Store.

Go to Apple’s CreateInstallMedia support page for up to date instructions.

Use the ‘createinstallmedia’ command in Terminal

I tried using Apple’s CreateInstallMedia instructions, and finally was able to create a working Install device and Utility drive per my additional instructions below. After letting Diskmaker X do it’s thing, the drives (when I try using the whole drive as the installer) and partitions (how I normally do it) are not seen by Mac OS as bootable in the “Startup Disk” System Preference or when holding down the Option key on boot/restart. Or if you want extreme speeds go for SanDisk SDCZ880-128G-G46 Extreme PRO 128GB USB 3.1 Solid State Flash Drive (This drive has a 380 MBps write and 420 MBbps read speeds for super fast installs)ĭiskmaker X has been problematic for me of late, I cannot seem to create a “bootable” USB drive from any of my Samsung USB drives.Try using a Sandisk Extreme Go 64GB USB 3.0 (3.1 Gen 1) Type-A USB Flash Drive – SDCZ800-064G-G46 (This drive has a 150 MBps write and 200 MBbps read speeds for faster installs).

Mac os disk utility set bootable drive