macOS Sierra 10.12 is the thirteenth major release from Apple, released on 20th September 2016 as a free upgrade via the Mac App Store. It is a digital download of approx 5 GB.
Whilst the process of downloading and installing an OS through the Mac App Store is straightforward enough, it’s painful for people with a slower internet connection, or if they’ve multiple Macs in their home.
If a Mac is having some issues a bootable USB of the OS can serve as an emergency disk. It is better than OS X Recovery as you don’t have to download the ~5GB installer data, first, to reinstall the OS or installer disk for Macs that does not support OS X Recovery.
In this tutorial, I'll show you two ways to install macOS Sierra onto a bootable USB drive.
Cost of Upgrade and Requirements
Before you get started, you’ll need
- Software—macOS Sierra 10.12 installer app
- Storage—USB 3.0 drive of 8GB or more, or an external USB hard drive, or a Firewire or Thunderbolt external hard drive
- A copy of DiskMaker X
Locate the macOS Sierra Installer
Open the Finder window and navigate to Applications > Install macOS Sierra. Proceed and follow the next steps for creating bootable USB drive.
Download macOS Sierra Installer
If you do not have the Install macOS Sierra app in the Applications folder, then you might have already upgraded to macOS Sierra. The installer application gets automatically erased after upgrading the Mac. To create a bootable disk, you need to have the installer app.
Step 1
Open the Mac App Store. Click on the Purchases tab, locate macOS Sierra and click the Download button.
Step 2
Once the download gets complete, you’ll see the installer window. Secondary-click, or two-finger tap with trackpad, on the running installer app from the dock and choose Quit.
Step 3
Open the Finder window and navigate to Applications > Install macOS Sierra. Proceed and follow the next steps for creating bootable USB drive.
Command Line Method
Step 1
Insert the USB drive. Open the Disk Utility app. Select the USB drive and click the Erase button.
Choose the Name as Untitled, Format as OS X Extended (Journaled) and select Scheme as GUID Partition Map. This option is used for all Intel-based Mac computers.
Click Erase, then click Done.
Step 2
Launch the Terminal app. Copy the following commandsudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ Sierra.app
Breakdown of the steps:
If you closely follow the above command, they rely on basic syntax
createinstallmedia --volume volumepath --applicationpath installerpath
- sudo—It’s a tool that is provided to allow regular (non-root) users to perform root tasks on a case by case basis
- createinstallmedia—Use this command in Terminal to create the bootable installer. To make this work, the app installer should be in the Applications folder. The OS installer path varies for Sierra, El Capitan, Yosemite, and Mavericks. Consult the Apple Support article for documentation
-
volume — Replace
volumepathwith the path to the USB drive or other volume. - applicationpath — This is the path to the Install macOS app
Step 3
Go back to the Terminal and paste the above command.
Step 4
Terminal will ask for the user password. Terminal doesn’t display characters when you type it in. Press Return.
Step 5
It asks for the confirmation to erase the drive. Type Y and press Return.
Step 6
You’ll see that Terminal starts erasing the drive, it then copies the installer files to the USB drive. This step can take few minutes to hours depending upon whether it is copying via USB 2.0 or USB 3.0.
Step 7
After copying, Terminal will display a Copy complete and Done notice. You can quit Terminal and the drive is ready to use.
Step 8
Eject the USB drive before removing it from the Mac.
Automated App Method
If you’re not into Terminal, then the automated method using an app is going to be easier for you.
Step 1
Insert the USB drive. Open the Disk Utility app. Select the USB drive and click the Erase button.
Choose the Name as Untitled, Format as OS X Extended (Journaled) and select Scheme as GUID Partition Map. This option is used for all Intel-based Mac computers. Click Erase, then click Done.
Step 2
Install DiskMaker X app. This app lets you create a bootable USB drive in a matter of minutes. You can use this drive to reinstall the OS on a freshly formatted drive, or install it on different Macs.
Step 3
Launch the DiskMaker app. It asks you the version of macOS you wish to make a boot disk of.
Step 4
If finds the copy of the Installer app in the Applications folder.
Step 5
Select the USB drive you wish to format. If you choose another kind of disk, only the chosen volume will be erased.
Step 6
DiskMaker X erases the disk.
Step 7
Enter the password of the user account.
Step 8
The process starts and can take some time to complete. It took around 5–6 mins to complete on Mac Mini 2012 with SSD and 10GB RAM copying to a USB 3.0 drive.
Step 9
The process completes. Now eject the USB drive before removing it from the Mac.
How to Boot from the Installer Drive
Step 1
Plug in the external USB drive you just created.
Step 2
Restart the Mac. Press and hold down the Option key while the Mac boots.
Step 3
The Mac will display the startup manager which will show you all the boot drives.
Click on the external USB drive and press Return.
Step 4
The Mac will display the OS X Utilities window. You can either install OS over the installed OS or format and reinstall the OS.
Conclusion
In this tutorial I have shown you two different ways to create a bootable USB drive for macOS Sierra. One is by command line and one using an app, DiskMaker X.
Both methods offer ease of use and flexibility, so it’s up to you to choose a method. Don’t forget to label the USB drive onto which you install macOS Sierra and make sure to keep them safe.
