Using the Mac's Recovery Disk Assistant

Use the Recovery Disk Assistant to create an external recovery volume

Recovery Disk Assistant

Part of the installation of OS X Lion and OS X Mountain Lion is the creation of a hidden recovery volume. You can use this recovery volume to start up your Mac and perform emergency services, such as running Disk Utility to repair a drive, browsing the web to find information on a problem you're having, or downloading a necessary update. You can even use the recovery volume to reinstall OS X Lion or OS X Mountain Lion, although this involves a full download of the OS X installer.

Information in this article applies to OS X Mountain Lion (10.8) and OS X Lion (10.7).

Limitations of the Recovery Volume

On the surface, the recovery volume seems like a good idea, but it has a couple of fundamental flaws. The most glaring problem is that the recovery volume is created on your startup drive. If the startup drive has hardware-based issues, it's conceivable that the recovery volume won't be accessible. That puts a damper on the whole idea of having an emergency recovery volume.

The second issue is that the OS installation process can run into problems when trying to create the recovery volume. This is especially true for those Mac users who don't use a straightforward drive setup; in some cases, the installer can't create the recovery volume at all.

The Release of OS X Recovery Disk Assistant

In response to these limitations, Apple released a new utility, the OS X Recovery Disk Assistant, which can create a recovery volume on an external hard drive or flash drive. This lets you place the recovery volume almost anywhere you want it.

The OS X Recovery Disk Assistant creates a new recovery volume by cloning the existing recovery volume. If your OS X installation was unable to create the original recovery volume, this new utility from Apple is of little use.

The second issue is that the OS X Recovery Disk Assistant only creates recovery volumes on external drives. If you have a second internal drive, which is possible on many of the Macs that Apple sells, including the Mac Pro, iMac, and Mac mini, you can't use it as a destination for your recovery volume.

Despite these flaws, it's still a good idea to have a recovery volume beyond the one initially created during the OS X Lion installation, and you do that with the Recovery Disk Assistant.

What You Need to Use the OS X Recovery Disk Assistant

Before you start, make sure you have everything you need.

  • A copy of the OS X Recovery Disk Assistant. That's an easy requirement to fulfill; the Recovery Disk Assistant is available from the Apple website.
  • A working OS X Recovery HD. The Recovery Disk Assistant uses a cloning process to create copies of the Recovery HD. If your OS X installation wasn't able to create the Recovery HD, the OS X Recovery Disk Assistant won't be usable. To find out whether you have a Recovery HD, restart your Mac while holding down the Option key. This forces your Mac to start using the startup manager, which displays all the bootable volumes connected to your Mac. You can then pick the recovery volume, usually named Recovery HD. After you select the recovery volume, your Mac starts up and displays the recovery options. If all is well, go ahead and restart your Mac normally. If you don't have a recovery volume, you won't be able to use the Recovery Disk Assistant.
  • An external drive to serve as the destination for the new Recovery HD. The external can be any drive that is bootable, including external USB, FireWire, and Thunderbolt-based drives, as well as most USB flash drives.
  • At least 650 MB of available space on the external drive. The Recovery Disk Assistant erases the external drive and then creates only a 650 MB space for itself, which is wasteful. It is a good idea to partition the external drive into multiple volumes. You can dedicate one volume to the Recovery HD and save the rest of your external drive to use as you see fit.

Preparing the External Drive

The OS X Recovery Disk Assistant completely erases the external target volume. If you use a 320 GB hard drive that is partitioned as a single volume, then everything currently on that drive is erased, and the Recovery Disk Assistant create a new single partition that is only 650 MB, leaving the rest of the drive unusable. That's a big waste of a perfectly good hard drive.

OS X Lion's Recovery Disk Assistant
Tom Nelson

You can fix this problem by first partitioning the external drive into at least two volumes. One of the volumes should be as small as you can make it, but larger than 650 MB. The remaining volume or volumes can be any size you want to take up the rest of the available space. If your external drive contains data you want to keep, back it up before you begin.

If you're willing to erase everything on the external drive, use Disk Utility to partition your drive.

The result is an external drive that has at least two volumes; one small volume for the recovery volume, and one or more larger volumes for your general use.

Make a note of the name you give to the smaller volume you create, the one for use as the recovery volume. The OS X Recovery Disk Assistant display volumes by name, with no indication of size. You need to know the name of the volume you want to use so that you don't erase and use the wrong volume by mistake.

Creating the Recovery Volume

With everything prepped, it's time to use the OS X Recovery Disk Assistant to create the Recovery HD.

OS X Lion's Recovery Disk Assistant
Tom Nelson
  1. Make sure the external drive is attached to your Mac and that it shows as mounted on the desktop or in a Finder window.

  2. Mount the OS X Recovery Disk Assistant disk image you downloaded from the Apple website by double-clicking its icon. It is probably in your Downloads directory; look for a file called RecoveryDiskAssistant.dmg.

  3. Open the OS X Recovery Disk Assistant volume you just mounted, and launch the Recovery Disk Assistant application.

  4. Because the application was downloaded from the web, you are asked if you want to open the application. Click Open.

  5. The OS X Recovery Disk Assistant license displays. Click the Agree button to continue.

  6. The OS X Recovery Disk Assistant displays all external volumes connected to your Mac. Click the volume you want to use as the destination for the recovery volume. Click Continue to start the creation process.

  7. Supply the requested administrator account password and click OK. The Recovery Disk Assistant displays the progress of the disk creation.

    The contents of the disk or partition are erased at this point.

  8. After the recovery volume is created, click the Quit button.

You now have a recovery volume on your external drive.

Test your new recovery volume to confirm that it's working by restarting your Mac while holding down the Option key. You should see the new Recovery HD as one of the startup options. Select Recovery HD and see if your Mac successfully boots and displays the recovery options. When you're satisfied that the Recovery HD is working, restart your Mac normally.