Professionals will value this advice on how to make a bootable Mac OS X 10.10 Yosemite install drive. Instead of installing Mac OS X as an internet download, you can install the download onto a USB stick and use the drive to install Mac OS X.

Bootable Mac OS X install drives are particularly handy if you have to install Mac OS X in a non-Internet emergency, or if you have especially slow internet connection (because it saves you having to re-download Mac OS X). The bootable install drive is also an invaluable tool for system admins because it enables you to install or upgrade Mac OS X on multiple Mac computers without having to wait for Mac OS X to download from the App Store each time.

In this feature we’re going to look at the different ways to create a bootable Mac OS X 10.10 Yosemite install drive.

See also:

How to format a storage drive for Mac

Top 5 ways to get OS X 10.10 Yosemite now and for free

What you need to make a bootable Mac OS X 10.10 Yosemite install drive

You’ll need a USB storage stick to make a bootable Mac OS X install drive. The USB stick should have at least 8GB storage space, and make sure there’s nothing on it that you need (it will be formatted during the creation process).

You will also need a copy of Mac OS X 10.10 Yosemite from the App Store. At the moment Apple developers will have a copy of the Mac OS X Yosemite Developer Preview 7 (GM) and the public has access to the Mac OS X Yosemite Beta 4.

It’s important to copy the Mac OS X install file from the Applications folder to another folder before you install Mac OS X (because the file is deleted from the Applications folder when you install Mac OS X 10.10 Yosemite). If you have already installed Mac OS X 10.10 Yosemite, then open App Store > Purchases and click Download next Mac OS X 10.10 Yosemite. The file will download to your Applications folder. Quit the install program when it launches and you’ll keep the install file in the Applications folder.

Different ways to create a bootable Mac OS X Install Drive.

There are three different ways to turn your USB stick into a bootable Mac OS X Yosemite install drive:

  • Disk Utility. This technique is a bit more long-winded, but much more user friendly. This is the best option for most people.
  • Use the installer’s built in createinstallmedia tool. This is a good option if you know your way around the Terminal app, and are a reasonably tech savvy.
  • Use Disk Utility in Terminal. If you are a real Unix geek this is the cool way to do it.

In this feature I’m just going to look at using the Disk Utility to create the bootable install drive. This is because it’s the easiest, and therefore, safest way to create a bootable install drive. Our sister site, Macworld.com has some information on using createinstallmedia and Disk Utility in Terminal.

Create a bootable Mac OS X Yosemite Install Drive in Disk Utility

You need to view hidden files in Mac OS X. Open an app called Terminal (located in Utilities) and cut and paste this text below (and press enter.) Don’t worry about the scary sounding ‘killall’ bit - it’s a geek’s way of saying ‘restart’ and it launches the Finder with hidden files displayed:

 

defaults write com.apple.finder AppleShowAllFiles 1 && killall Finder

 

You should see some files appear on the desktop such as “.DS_Store”

Show Package Contents

Now Follow these steps to create a bootable Mac OS X Yosemite Install drive in Disk Utility:

  1. Open a Finder window and locate the Install OS X Yosemite Beta file (in the Applications folder). It may be called something else if you are running the Developer edition.
  2. Right-click on Install OS X Yosemite Beta and choose Show Package Contents.
  3. In the Folder that appears navigate to Contents > Shared Support and locate a file called installESD.dmg.
  4. Double click InstallESD.dmg to mount the volume in Mac OS X. A Finder window will open. Note the file inside called BaseSystem.dmg.
  5. Open Disk Utility (you can find it by clicking Go > Utilities).
  6. Drag the BaseSystem.dmg file from Finder to the Source sidebar (the list of volumes on the left-hand side). Adding BaseSystem.dmg to the Source list
  7. Click on BaseSystem.dmg in the sidebar and the Restore tab.
  8. Locate the USB Flash drive in the Source sidebar, underneath it will be the Volume for the drive. Click and drag this volume from the sidebar to the Destination field. Drag USB volume to Destination field
  9. Click Restore and Erase. Enter your Admin password and click OK. Note that this erases all the data on the USB Stick.
  10. A progress bar will appear at the bottom of the Disk Utility. Wait for it to finish (typically 5-10 minutes).
  11. The USB drive will mount on the Finder. Open the volume (it should be called OS X Base System) and open System > Installation. Locate an alias file called Packages. Delete it.
  12. Open the OS X Install ESD volume and locate a folder called Packages. Drag it to the Installation folder on the OS X Base System volume.
  13. Open the OS X Install ESD volume and find files BaseSystem.chunklist and BaseSystem.dmg. Drag these to the root (base) level of the OS X Base System (do not place them inside the System or Installation folders).
  14. Eject the OS X Install ESD Volume. Store it safe for when you need it.

Erase drive and restore Mac OS X Install files

 You should now restore files to the hidden state (this is a good precaution that prevents you from accidentally moving, or removing, important files. Open Finder and cut and paste this line into it:

 

defaults write com.apple.finder AppleShowAllFiles 0 && killall Finder

 

You now have a Yosemite boot drive that can be used to install Mac OS X Yosemite onto a Mac. Insert the boot drive into a USB port on a Mac and start it up while holding down the Alt key to access it. This will enable you to install Mac OS onto a Mac without having to download the Install file each time.

Note. We believe this same process will work when Apple releases Mac OS X 10.10 Yosemite to the public, but we will be sure to check and update it.

Also read our comparison of Yosemite and Mavericks