Installing OSX with a Memory Stick

appleYosemite is a free download that you can install over the top of your existing installation.  This article describes the process of creating a USB boot disk, so that you can install it from scratch.


You will need an 8GB USB memory stick.  Your Mac will need a minimum of 2GB memory. Yosemite will run on the following models...

  • iMac (Mid-2007 or later)
  • MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)
  • MacBook Pro (13-inch, Mid-2009 or later), (15-inch, Mid/Late 2007 or later), (17-inch, Late 2007 or later)
  • MacBook Air (Late 2008 or later)
  • Mac Mini (Early 2009 or later)
  • Mac Pro (Early 2008 or later)
  • Xserve (Early 2009)



Start by clicking the App Store.

  1. Search for OS X Yosemite.
  2. Download the free installer.
  3. This will download OS X Yosemite to your Applications folder.


Format USB Stick

Plug in your 8GB memory stick.  First we need to format the USB disk.

  1. Go to Applications > Utilities.
  2. Start Disk Utility.
  3. Select your USB device.
  4. Select the Partition tab.
  5. Choose 1 Partition from the Partition Layout drop-down.
  6. Choose Mac OS Extended (Journaled) as the Format type.
  7. Select Options for the newly created partition and GUID Partition Table (for Intel).
  8. Name it Yosemite.
  9. Click Apply.


Create the Installer

  1. Start Terminal.
  2. Run the following command.
sudo /Applications/Install\ OS\ X\ --volume /Volumes/Yosemite --applicationpath /Applications/Install\ OS\ X\ --nointeraction

 The USB stick should be ready in about 30 minutes.


Boot Procedure

You are now ready to boot to USB stick.  Remember that this will wipe your hard drive.

  1. Power on your iMac.
  2. Hold down the Option key.
  3. Choose the Install OS X Yosemite disk.



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