UPDATE 09/2018: Create a Bootable macOS Mojave Install Drive with DiskMaker X 8
Apple has made macOS installations (and those for Mac OS X before it) as simple as hitting a download link, but what if you’d like to have a bootable disk drive with which to install macOS Sierra on a number of different Macs? Fortunately, there’s a quick and free solution in the form of DiskMakerX, which has just become available in a macOS Sierra-compatible version. In this post, we’ll demonstrate how to create your own bootable install drive.
The first thing you’ll want to do is download DiskMakerX 6 to a Mac using the link above. Note that although DiskMaker X is free of charge, donations are accepted — you can help support a useful utility by sending the developers what you feel the app is worth.
Install DiskMaker X 6
To install DiskMaker X 6, find the installer disk image file — usually in the Downloads folder — and double-click it. The disk image is mounted, and the following screen appears:
Installation is simple — just drag the DiskMaker X 6 icon to the Applications folder alias as shown on the installer screen. Within seconds, the app is installed and ready for launch. But don’t double-click that app icon yet…
Download the macOS Sierra installer
Chances are good that when macOS Sierra was installed on your Mac, the installer file disappeared. That’s OK — you can download it by launching the Mac App Store, locating and clicking on the link for macOS Sierra in the right sidebar, then clicking the “Download” button. A copy of the installer is downloaded and saved into the Applications folder.
Get a suitable USB thumb, USB, Thunderbolt, or FireWire drive
DiskMaker X will require at least 8GB of capacity on whatever drive you select to be your bootable install drive. USB thumb drives are adequate for the task; this OWC 16.0GB Dual USB Flash Drive (see image above) is perfect, and it’s only $9.99. Likewise, a fast 500GB OWC Mercury On-The-Go Pro USB 3.0 drive ($94.99) is a lot speedier for installation, the same drive in a FireWire 800 version ($119.99) is handy with Macs that support that connection, and for the best possible speed while performing mass installations of macOS Sierra from the drive, you’ll want to look into something like this 1TB LaCie Rugged Thunderbolt drive ($179.99).
Note that whatever is on the drive when you create your bootable macOS Sierra Install Drive will be erased. If you plan to use the same drive to carry other utilities or tools, or to serve as a backup drive, you’ll need to do that after the bootable install drive is created.
Launch DiskMaker X 6
Make sure that your drive is attached to your Mac and visible from the Finder, then launch DiskMaker X 6. As you can see in the screenshot below, DiskMaker X 6 allows the creation of bootable disks for Mac OS X Yosemite, Mac OS X El Capitan, and of course macOS Sierra.
In this example, we’re making a macOS Sierra boot disk, so click the highlighted (blue) button. If the “Download the macOS Sierra installer” step was bypassed, DiskMaker X 6 responds with an error message and quits, so make sure that you have the installer on your Mac. When the installer is on your Mac, DiskMaker X 6 displays a dialog asking which copy of the installer you want to use:
The copy we are using is in the Applications folder, so click the highlighted (blue) button marked “Use this copy”. Next, DiskMaker X 6 asks for the type of disk you’ll be using for your bootable disk (see image below). Note that if you’re using a 8GB (or larger) USB thumb drive, it will be completely erased. DiskMaker will erase any complete volume that you signify, so if you wish to make a disk that can install Yosemite, El Capitan, and Sierra, consider using Disk Utility (found in the Applications/Utilities folder) to partition the drive into three separate volumes, one for each operating system version.
For this example, we’re using a small RAID device so clicking “Another kind of disk” is appropriate. As seen in the following screenshot, the drive “RAID1” was selected by clicking on its name, and then “Choose this disk” was clicked.
This is your last chance to make sure that you really want to erase the disk and turn it into a bootable drive. When you’re sure, click the “Erase then create the disk” button (see below):
Once the blue button has been clicked, a lot happens very quickly. Since the Mac requires administrator privileges in order to make the new boot drive, you’ll be reminded that the admin user name and password will need to be entered (see below) and then a standard Mac login dialog appears.
During the disk creation process temporary windows will open and close, files are copied, and a lion roars. When you hear the lion’s roar, you know that DiskMaker X 6 has completed the process and a dialog informs you of that fact. At this point, it’s possible to either reboot your Mac while holding down the Option (Alt) key to select the drive, or use System Preferences > Startup Disk to select it.
You can also quit and do the macOS Sierra upgrades at a later time, and/or make a donation towards the care and feeding of the DiskMaker X developers. There is another way to make a bootable installation disk that requires familiarity with the Mac command line, but DiskMaker X just makes the process much more “Mac-like” and transparent.