The instructions below are for Windows 10, but other versions of Windows from Windows 7 and up can also format an external drive as exFAT for use with Mac as well.
Advertisement As you may know, you can reinstall macOS on your computer via the internet recovery. But did you know that you can create a bootable USB drive to install macOS from? This will let you boot your Mac from a different source if it won’t work normally, and makes installs on multiple machines easy. Let’s see how to do this. Choosing a USB Flash Drive for Installing Mac USB flash drives are cheaper than ever, so you won’t have to spend much for this task.
However, make sure to buy a name-brand flash drive (like SanDisk, Kingston, or PNY) from a reputable store. Stay away from super-cheap drives with suspiciously high storage on sites like eBay. These drives have their firmware hacked to report a false size to your operating system. Not only will the transfer speeds be painfully slow, but using them may also result in loss of data or even a damaged USB port.
Also, check to see what ports you have on your Mac. The 12″ MacBook has a single USB-C port, while MacBook Pro models from 2016 and later feature USB-C ports exclusively. Fortunately, there are USB-C drives available, or you can use a USB-C to USB-A adapter. It’s best to go with a USB 3.0 drive, with a minimum size of 16GB. The is good overall value for the money; we’ve highlighted for more options.
$9.99 Formatting Your USB Flash Drive You can only create a bootable installer for macOS on a Mac. If you’re using a flash drive that already has data on it, make sure to back up any important files as you’re going to erase everything in a moment. Navigate to Applications Utilities, and open up Disk Utility. You should see your flash drive under the External section in the left pane. After selecting it, click on the Erase button along the top.
Choose a friendly name (which you’ll use later), and make sure to choose Mac OS Extended (Journaled) for the format. Finally, click Erase and you’re done with this step. Downloading the macOS Installer To download the macOS installer, open the App Store and search for your version of macOS. Click on the Download button if you’re on High Sierra or earlier.
MacOS Mojave is slightly different, as it opens up your System Preferences to download the installer. This is because one of is a new way of installing updates.
The experience of building the USB with DiskMakerX7 was painless. I am now able to boot to a screen with two icons like the one shown in this article. At this point, I select the USB drive that is named 'Install OS X High Sierra' and that takes me to the menu with 4 choices. When I go into Disk Utilities, I am able to re-format the 500GB HD in the iMac and it automatically creates a new volume. I named my volume 'Abyss'. Then I return to the 4-choice menu and select 'Install MacOS', and click the Continue button. The Continue button turns gray - forever.
Yes, I have verified that this iMac is eligible to use High Sierra. What could be wrong? Is it possible that I need a newer OS X Base System? Can that be upgraded?
Why a flash drive? A bootable external or internal hard drive works well for desktop Macs but presents a cumbersome problem for notebook Macs. A flash drive is a simple, inexpensive, and portable emergency boot device that can handle OS X or the macOS. Heck, it can even have both operating systems installed, letting you use the emergency USB flash drive to boot any of the Mac's you may have. Even if you don’t use a notebook, you may want to have a bootable USB flash drive on hand.
What You Will Need. Insert the USB flash drive into your Mac’s USB port. Launch Disk Utility, located at /Applications/Utilities/.
In the list of drives attached to your Mac, select the USB flash drive device. In our case, it’s called 14.9 GB SanDisk Cruzer Media. (Like lumber, hard drives and flash drives are actually slightly smaller than their specs would have you believe.). Click the Partition tab. Select 1 Partition from the Volume Scheme drop-down menu. Enter a descriptive name for your flash drive; we chose Boot Tools.
Select Mac OS X Extended (Journaled) from the Format drop-down menu. Click the Options button. Select GUID Partition Table from the list of available partition schemes.
Click the Apply button. A sheet will drop down, warning you that you are about to erase all data from the disk. Click Partition. Disk Utility will format and partition your flash drive. Quit Disk Utility.
Before you begin the installation, a few notes about the process. As we mentioned earlier, USB flash drives are much slower at writing data. Since the installation process is all about writing data to the USB flash drive, it’s going to take quite some time. When we performed the installation, it took about two hours. So be patient, and don’t worry about how slow some of the processes seem; this is normal. You can expect to see plenty of beach balls and slow responses as you work your way through the installation process.