How to create an installation USB for Mac OS X Yosemite

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How to create an installation USB for Mac OS X Yosemite

This procedure works for Yosemite, but it should also work for the previous version of Mac OS X (Mavericks or Mountain Lion). But it will not work for Mac OS 10.6 (Snow Leopard).

Mac OS X Yosemite official page


The compatible Macs:
  • iMac (Mid 2007 or newer)
  • MacBook (late 2008 aluminum chassis, early 2009 or newer)
  • MacBook Pro (mid late 2007 or newer)
  • MacBook Air (late 2008 or newer)
  • Mac mini (Early 2009 or newer)
  • Mac Pro (Early 2008 or newer)
  • Xserve (Early 2009)

The requirements:
  • OS X 10.6.8 or higher
  • 2GB of memory
  • 8 GB of available space
  • Some features require an Apple ID
  • Some features require a compatible Internet package; subscription charges may apply.


Recommended configuration

This will allow Mac OS X to automatically import the data already present on the Apple server during installation/upgrade. There procedure is optional and the step involving the creation of the iCloud account can be skipped during the installation of Yosemite.
You will also need a 8GB USB key.

STEP 1 - Download Yosemite

  • Launch the App Store and sign in with your iCloud credentials.
  • Click on OS X Yosemite.
  • Click on the Download button (5.2 GB).

Once downloaded:
  • The installation window automatically launches.
  • Do not click on "Continue".
  • Close the installation.
  • Go to the Applications folder and locate the installation package: "Install OS X Yosemite"
  • At this point you can the application to an external storage medium. The goal is to keep intact for possible future needs.
  • Leave the original app in the Applications folder.

STEP 2 - Prepare the USB key

  • Connect your USB key (not to the keyboard, but to the Mac itself) - run the Disk Utility located in Applications/Utilities ...
  • In the left pane of the Disk Utility, select your USB key.
  • On the right side of the window, click on the "Partition" button.
  • In the "Partition Scheme" section, click on the "Current" button.
  • Select "1 Partition".
  • Click on the "Options" button.
  • Select GUID and click on the "OK" button.
  • Check that the chosen format is "Mac OS Extended (Journaled)"
  • Name the key as yosem.
  • Validate
  • At this point the key is ready.

STEP 3 - creating the installation USB

  • Open the Terminal application located in Applications / Utilities ...
  • Enter the below command:

sudo /Applications/Install\ OS\ X\ --volume /Volumes/yosem --applicationpath /Applications/Install\ OS\ X\ --nointeraction 
  • Confirm with "Enter" key
  • Upon request, provide your administrator password
  • Let the process unfold. It takes approximately half an hour.
  • Your installation USB key is ready!

Update from a previous version

Mac OS X Snow Leopard: If you are running Snow Leopard (10.6.x), make updates from the Apple menu > Software Update ...
  • Your system will be updated to OS X 10.6.8, from there you can get Yosemite from the Mac App Store.
  • Install Yosemite directly on your Mac.
  • You will need to re-download Yosemite to get the installer.
  • If you have Leopard (Mac OS 10.5) and want to upgrade to Yosemite, you must first install OS X Snow Leopard.
Jean-François Pillou

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