Updated
August 29, 2016.
OS X Yosemite is a free download that comes to your Mac from the Mac App Store in the form of an installer that starts up automatically. If you follow the onscreen instructions, you'll end up with an upgrade install of OS X Yosemite on your startup drive. The process is quick, easy - and has a minor flaw.
What if you want to perform a clean install, completely erasing your startup drive? Or perhaps you'd like to have the installer on a bootable USB drive, so you don’t have to keep downloading it every time you wish to upgrade one of your Macs?
The answer is you can't, at least not if you follow the onscreen instructions. The problem is that the installer is deleted as part of the upgrade process. This means you can't upgrade another Mac without downloading the installer again. It also means you don't have an easy method of performing a clean install, because you don’t have a bootable copy of the installer.
To correct this basic flaw, all you need to do is quit the installer when it automatically starts up after the download is complete, and then use one of two methods for creating a bootable USB flash drive that contains the OS X Yosemite installer.
Two Methods for Creating a Bootable Installer
There are two methods for creating the bootable installer. Although I prefer using a USB flash drive as the destination for the installer, you can use either method to create a bootable version of the OS X Yosemite installer on any bootable media, including hard drives, SSDs, and USB flash drives.
The first method we covered makes use of a hidden Terminal command that can perform all the heavy lifting for you, and produce a bootable copy of the installer using a single command.
You'll find complete instructions for this method in the article:
There is also a manual method of performing the same process, using the Finder and Disk Utility. This article will take you through the steps to manually create a bootable copy of the OS X Yosemite installer.
What You Need
- OS X Yosemite installer. You should have already downloaded the installer from the Mac App Store. You'll find the download in the /Applications folder, with the file name OS X Yosemite Beta. (Please note: We'll update the name of the installer file once OS X Yosemite is released to the general public. Currently, these instructions will work for the public beta version of Yosemite.)
- A USB flash drive or other suitable bootable device. As I mentioned above, you can use a hard drive or an SSD for the bootable device, although these instructions will refer to a USB flash drive.
- A Mac that meets the minimum requirements for OS X Yosemite.
One final note: If you already installed OS X Yosemite onto your Mac, you may still wish to create a bootable copy of the installer as a troubleshooting tool, or to make additional Yosemite installations easier. In order to proceed, you'll need to re-download the Yosemite installer from the Mac App Store. You can force the Mac App Store to allow you to download the installer again by following these instructions:
All set? Let's get started.