Select the USB drive on the left menu, Erase tab.Plug your USB drive into your Mac and launch the Disk Utility application.Double-click InstallESD.dmg to open (or mount) it on your Desktop.Navigate to Contents > SharedSupport, then look for the filename 'InstallESD.dmg'.Look for the file called 'Install OS X Mountain Lion', Right-click and select Show Package Contents.Create bootable OS X Mountain LionĪfter your download is done, let’s proceed to making a bootable USB drive with your OS X Mountain Lion in it. Note: This may take up between 10 and 60 minutes, depending on the speed of your Internet connection. If you’ve previously purchased a copy of Mountain Lion, don’t worry, you will not be recharged. Re-enter your App Store credentials if required.Look for OS X Mountain Lion, hold down the Option key and click Download.

Launch the App Store and go to the Purchases tab.Here’s how you can download and obtain a soft copy of Mountain Lion. The installer you downloaded from the App Store automatically deletes itself after you’ve successfully upgraded (or install) your Mac. Re-download Mountain Lion Installerįirst, grab hold of a copy of the Mountain Lion installer file. The main drive in this list is No.While I was doing maintenance for my Mac, using the Maintenance app, the app told me that my. You can make a bootable USB drive or disk from the Recovery Partition, but involves a small trip to the Terminal….ġ) Launch Terminal from /Applications/Utilities and run: diskutil list If you bought a new machine from Apple you have OS X 10.8 already installed – but no back up disk! and since you haven’t bought the OSX Lion 10.8 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, to boot from it you need to restart the machine and when it starts to boot hold down “command” + “r” keys.įrom recovery mode you can run Disk Utility, access the command line, get online help and do a restore from a Time Machine backup and re-install Mountain Lion leaving all your other files intact – it just replaces the core operating system. On every OS X 10.8 Mountain Lion install a hidden partition is present to enable a method for Mountain Lion to be reinstalled on the machine, it is known as the Recovery Partition or drive and is 650mb in size.

Os x mountain lion bootable usb