There we select InstallESD.dmg as the source and the SD card partition as the destination. In our case, an SD card, from Disk Utility we select the unit and create a partition with a GUID partition table. The only thing we have to keep in mind are two details, the first is that the minimum capacity must be 8GB the second is that the partition table used must be GUIDs for Intel-based Macs to detect them as boot disks. We are going to prepare our boot disk that could be an SD card, a USB memory, a hard disk or even a DVD. We move that file to the desktop, close the Finder windows, and open Disk Utility. There is the file that we will need to create our installation disk, InstallESD.dmg. There we locate the downloaded file, with the second mouse button we click on the icon and select Show package content.Ī Finder window will open where we will see a folder called Content, we open it and then we open SharedSupport. When OS X Mountain Lion is downloaded and the update process begins, what we will do is close that window and go to the applications folder. What's more The advantage of this method is that we will be able to update the rest of our Macs more quickly. The truth is that an update should not cause problems but if OS X is already doing strange things to you, it may be a good idea to do a clean installation.

If there is no change when Mountain Lion is available in the Mac App Store we can download the installer that will allow us to update our current version, either Snow Leopard or Lion. 2 Installing OS X Mountain Lion from scratchĬreating the OS X Mountain Lion installation media.1 Creating the OS X Mountain Lion installation media.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.

Install mountain lion from usb