Turns out Apple knows what’s best for you, and won’t let you use a USB thumb drive if your Mac has an optical drive. Unnecessary restriction at its finest.
A co-worker has an Early-2011 MacBook Pro that he used primarily as a Windows machine. (I know, I know… Don’t ask me…) His hard drive died and he needed to reinstall OS X and Windows. But… He only had a Windows 7 ISO disc image, and didn’t have a blank DVD, but had a couple USB thumb drives that we should be able to use to create a bootable install volume – after all, how do Macs with no optical drive install Windows (which, as of this writing, is all but one of them – the lowly non-Retina 13″ MacBook Pro)?
Luckily I was able to piece together some hacks from various sources across the Internet, and I decided to document them here, for anyone else that finds themselves in this same situation…
I’ve successfully done this with Windows 7 on OS X 10.9 Mavericks, but it should also work with 10.8 (minus the need to re-sign the Boot Camp Assistant app), 10.10, and 10.11, and the flavors of Windows that those versions of OS X support.
Here are the steps I followed – DO AT YOUR OWN RISK. Don’t come crying to me if you destroy all the data on your OS X partition ’cause you clicked the wrong thing somewhere… PAY ATTENTION.
- Procure Windows install ISO file
- Acquire USB thumb drive (8 GB or larger)
- Download TextWrangler (optional, but makes editing the .plist file easier)
- Note your Mac’s Model Identifier as indicated in the Hardware Overview in OS X’s System Information app. (Choose About This Mac in the Apple Menu, then click More Info… then click System Report…)
- Navigate to the Boot Camp Assistant app’s “Contents” folder (put the path name in quotes since it contains spaces):
cd "/Applications/Utilities/Boot Camp Assistant.app/Contents"
- Edit the Info.plist file in that folder using your editor of choice. If you have TextWrangler installed, you can run the following command to open in the TextWrangler GUI:
sudo edit Info.plist
You can also use the bare-bones text editor Nano that is part of OS X’s core software
sudo nano Info.plist
- Add the string for the Model Identifier base (before the comma) as noted in step 4 to the top of the PreESDRequiredModels and PreUEFIModels arrays. If your Mac is an iMac12,2, then should look like this (in OS X 10.9):
<key>PreESDRequiredModels</key> <array> <string>iMac12</string> <string>MacBook7</string> <string>etc...</string> </array> <key>PreUEFIModels</key> <array> <string>iMac12</string> <string>MacBook7</string> <string>etc...</string> </array>
- Remove or comment-out the line where your model is listed under the PreUSBBootSupportedModels array. I just commented mine, and it worked fine – it looked like this:
<!-- <string>iMac12,2</string> -->
- Save the file.
- If you’re running 10.9 or later, you’ll need to re-sign the Boot Camp Assistant app by running this command from the terminal:
sudo codesign -fs - /Applications/Utilities/Boot\ Camp\ Assistant.app
- Launch your newly patched Boot Camp Assistant app and choose the newly available option to “Create a Windows 7 or later version install disk” o create your boot drive.
- After that finishes (it could take a while – you’re copying many many GB of files and adding Apple-specific bits so it can boot your Mac), go back to Boot Camp Assistant and download the Boot Camp software (unless you’ve already done this), then “Install Windows 7 or later version” onto your Mac.
- Do the Windows installation cha-cha. Go out to dinner, go see a movie, then come back and HOPEFULLY your Windows installation will be finished by then.
I think that’s it. There are some other steps to actually doing the Windows install through Boot Camp, and Apple has that documentation, so go look it up. But this should get you a bootable thumb drive for your computer that you can use instead of an optical disc.