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Create an Emergency OS X Boot Device Using a USB Flash Drive

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Boot OS X From a USB Flash Drive: What You Will Need
Close up of usb flash drive
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A bootable copy of OS X on a USB flash drive is a great emergency backup tool to have on hand. It allows you to be ready to go almost immediately should anything happen to your existing startup drive.

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 OS X boot device. Even if you don’t use a notebook, you may want to have a bootable USB flash drive on hand.

What You Will Need


  • An Intel-based Macintosh

  • An install DVD of OS X 10.5 (Leopard), OS X 10.6 (Snow Leopard) or the downloaded installer image of OS X 10.7 or later

  • A 16 GB or larger USB flash drive

I’ve chosen to use a 16 GB or larger flash drive for two reasons. First, a 16 GB flash drive is large enough to accommodate the current minimum amount of space required to install OS X directly from the install DVD. Eliminating the need to pare down the OS to get it to fit on the USB flash drive significantly simplifies the installation process. Second, the cost of USB flash drives is falling. A 16 GB USB flash drive is large enough to install both a complete copy of OS X and some of your favorite applications or recovery utilities, making it a budget-friendly emergency device that can boot your Mac and possibly repair or recover its data and get it running again.

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