Make a Bootable USB Drive from OS X Lion Using the Recovery Partition

August 2, 2011 16 Comments

On every OS X Lion installation a hidden partition is created to enable a method for Lion to be reinstalled on the machine, it is known as the recovery partition or drive and is 650mb in size.

If you bought a new machine from Apple you have OS X 10.7 already installed – but no back up disk! and since you haven’t bought the OSX Lion 10.7 App from the App store you can’t re-download it – so thats why you have the recovery drive as a partition in your main hard drive and to boot from it you need to restart the machine holding down “command” + “r” keys.

From recovery mode you can run Disk Utility, get online help and do a restore from a Time Machine backup and re-install Lion leaving all your other files intact – it just replaces the core operating system.

You can make a bootable USB drive or disk of the recovery drive, but involves a small trip to the Terminal….

1) Launch Terminal from /Applications/Utilities and run:

diskutil list

The primary drive in this list is No.2 with the “Identifier” of disk0s2, the boot recovery drive is disk0s3

me@[~/Desktop]: diskutil list
/dev/disk0
   #:                       TYPE NAME               SIZE       IDENTIFIER
   0:      GUID_partition_scheme                   *250.1 GB   disk0
   1:                        EFI                    209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD       249.2 GB   disk0s2
   3:      Apple_Boot Recovery HD                   650.0 MB   disk0s3

We can also identify the recovery drive by the name and the size – set at 650mb

2) Mount the drive:

 diskutil mount /dev/disk0s3

Output should be:

Volume Recovery HD on /dev/disk0s3 mounted

Now the Recovery HD is mounted in the Finder and you can see it in the sidebar under Devices
Navigate to it from the sidebar – Recovery HD/com.apple.recovery.boot/BaseSystem.dmg.

recovery-finder-osx-lion

3) Doubleclick BaseSystem.dmg to mount it also in the sidebar. This will mount the volume ” Mac OSX Base System”

mac-osx-lion-base-system

4) Open Disk Utility in /Applications/Utilities

5) Put in a 2GB+ USB drive, let Disk Utility load it. The USB drive needs to be formatted as Mac OS Extended Journaled, if its not, its time to format it in Disk Utility…

usb-format-osx-extended-lion

6) Finally in still in Disk Utility, select the “Restore” tab - drag the mounted volume “Mac OSX Base System” into the Source field and drag the USB drive “Volume” (mine is called SuperBootUSBDrive) to the Destination.

restore-volume-osx-usb

7) Click Restore – 25 minutes later – One bootable USB drive

Your bootable USB drive will be called “Mac OS X Base System” after the restore is complete. Now to boot from it just select it as the Start Up disk in System Preferences or hold down option key on boot and select it from the choice of bootable devices.

If you have downloaded the Lion App from the App Store then you can also make a boot disk/drive from this, guide is here, you need to make the boot drive/disk before you install the Lion App, as the installer is deleted after running it. Thats why the guide here can get you out of trouble.

Couple of footnotes on this – Apple has released a knowledgebase article about the recovery partition, also just released from Apple is an app that will do the same as above.

Update For Newer Models – hidden BaseSystem.dmg

If you have the latest models from Apple that came already shipped with OSX 10.7, then you may not have the “BaseSystem.dmg” but instead see a “BaseSystem.chunklist” , the “BaseSystem.dmg” is there it’s just hidden.

To show it so you can see it in the finder – go to Terminal – enter:

$ cd /Volumes/Recovery HD/com.apple.recovery.boot

$ chflags nohidden BaseSystem.dmg

Now it will be visible in the Finder.

Imaging, OS X, Tech

boot, image, lion, OSX, recovery, usb

Stop Spam Subscriber New User Registrations on WordPress

Use a Different DNS Nameserver with Dig and NslookUp

James

Hi thank you for posting this nice article. I am new to Macs and just got one of the new Airs.

I have a few questions. Correct me if I’m wrong the way I understand it works is that you would boot with this “recovery” USB key (which contains the “Mac OS X Base System”) and it would load the Mac OS X Utilities app. From there you can select Install/Reinstall and it would download OS X Lion from Apple (several GB like 4 GB?)

Is that correct? If you download the OS X Lion app from the AppStore and made a USB key from it, does it have the same contents as this “recovery” USB key? For example, if you downloaded the app from the AppStore does it have to download the entire OS X Lion from Apple or it is contained on the USB key that you could make from the downloaded app?

I’m trying to make a USB key that would contain the entire OS X based on my new Air which came with OS X Lion pre-installed. Is this possible? Also, one more question. Don’t the new Macs come with a built-in “Internet Recovery” feature that would automatically download the “Mac OS X Base System” from Apple and from that point on the process of reinstalling OS X Lion would be the same as if you had booted with this “recovery” USB key? I have accessed the recovery feature by holding down Command-Option-R while booting. I think it allows you to install OS X Lion on the new Macs (if you replaced the hard drive for example) without having a bootable USB key and without having OS X Snow Leopard so that you can purchase & download the app from the AppStore?

thanks for your help!

Neil Gee

Hi James,
Yes you are correct the “Recovery” Partition is a part installer – it needs to connect with Apple to get the missing components, so a Internet connection is crucial.

However the downloaded Lion App from the App Store is the real deal, it has all components and does not need to call home, but the thing is after installation the original App is deleted – so it is best to make a bootable disk of this before it is installed, I cover this here.

On your last note – any machine with a Lion installation has the 650mb partition which allows it to boot from the recovery partition and reinstall the full OS part from the recovery partition and also connecting back to Apple.

For a full installer with no internet connection required, its best to make the boot image from the Lion App.

Edc45acp

Ok this has been covered many times, “Make bootable USB from App store download”. But what I want to do is make a bootable USB key on a Mac that lion came preinstalled on. Just how do I do that.
Thanks

http://coolestguyplanettech.com Neil Gee

if you mean – make a bootable usb drive – then you can use Carbon Copy Cloner, but to run an OS off a USB as the boot volume is going to be seriously slow but as a back up device is OK.

Darren

After I did the steps in this tutorial, I was able to do everything successfully, and I thank you for that. Now, whenever I turn on my Mac holding the option key, it will show Macintosh HD and also Recovery HD. I ejected Recovery HD from Finder, but how do I make it hidden again so it does not show Recovery HD whenever I hold down the option key at startup. Thank you!!

Anonymous

Hi Darren,
It will always show “Recovery HD” if you hold the option key down at start up, as the option key start up shows all available boot devices and since the “Recovery HD” is a hidden bootable partition it will always show.
If you boot normally without the option key, it will remain hidden.

Pingback: Apple OSX Restore Offline [MBA 2011]
Anonymous

This is great, but is there a way that I can create a MacOS Lion bootable disk that boots to the finder and lets me run 3rd party disaster recovery tools like Disk Warrior, Drive Genius, etc.?

Anonymous

From the Recovery HD you can run Disk Utility, if you need to run more than I suggest making a clone of your HD with Carbon Copy Cloner, boot from that and then run whatever you like.

Anonymous

Just bought a MBA 2011 with Lion pre-installed. However when the recovery HD drive is mounted there is no BaseSystem.dmg file but a BaseSystem.chunklist. All the other files in the com.apple.recovery.boot are as per the screenshot above. Any ideas?

Edwin

You can see this (BaseSystem.dmg) if you go into Terminal and type the command to show hidden files:

defaults write com.apple.Finder AppleShowAllFiles TRUE

Anonymous

Spot on with this!

JT

I confirm tha there is no .dmg only a .chunklist file. So, now what???

Anonymous

Try the update I added to the blog post

Starlene

I run my OS Lion 10.07 from a 32GB pendrive and it loads better than the airport. Try it.
http://coolestguyplanettech.com Neil Gee

You can

Make a Bootable USB Drive from OS X Lion Using the Recovery Partition

Subscribe 2 Coolest Guy Planet Posts

ars technica

mac surfer