Clean Install of OS X Mountain Lion: The preparation
In any case, you should make before you reinstall a Backup of your data and programs. This is the most convenient with Time Machine. The best tips to this Backup method, read here. After that, you prepare your new installation.
- Open the App Store and download Mountain Lion download. They don't choose directly the Installation, but load only the installation Image on your Mac. Should you will be displayed with no Option to abort the installation process after the download.
- Open the Finder and navigate to the applications folder. There click with the right mouse button (or with ctrl-key and left-click) the program "OS X Mountain Lion Installation".
- In the context menu, select "show package contents". It is a new Finder window now opens. Navigate to the folder "Contents/SharedSupport". There you will find the file "InstallESD.dmg“.
- Open the disk utility. You now need a USB Stick with at least six gigabytes. You plug this into a free USB Port.
- Click on the disk utility on the USB-Stick. Lay on the tab "Partition", a Partition with Format "Mac OS Extended (Journaled). Under options, set the partition scheme to "GUID partition table". Finally, click on "Apply". Your USB Stick will now be deleted.
- Select in disk utility the Partition you have just created. Then click the tab "restore". As the target medium, select your USB-Stick. Drag & Drop to insert the "source" the file you are looking for "InstallESD.dmg" and then select "restore". You now have an installation medium, with a Clean Install of OS X Mountain Lion can perform.
Clean Install of Mountain Lion
Clean Install of OS X Mountain Lion: The Installation
Check whether you have backed up all your data and programs. In the next step, your System will be completely deleted and set up again.
- Start your System with plug-in installation-USB-Stick. Holding the alt-button pressed down until a selection menu is displayed. In addition to your old Installation, you can also find the USB-Stick. Select this and boot to the installation routine.
- After the boot process, select the language. Then you come in the main menu of the installation routine. Select disk utility and click on "Next".
- Select in disk utility the hard drive on the OS X Mountain Lion will be installed. On the tab "Partition", select a Partition in the Format "Mac OS Extended (Journaled)" with the Option "GUID partition table" and apply the Changes. The hard drive is now completely deleted. Useful tips for hard disk utility to find it here.
- Quit the disk utility. You are now in the main menu of the Installation. Click on the actual reinstallation of Mountain Lion. In the Installation, select the just-deleted disk as the destination disk and start the Installation.
- After the completion of the Installation reboot your System and make the necessary disclosures. Your data or programs to play back, it's best to use migration assistant from OS X Mountain Lion, and select the source as your Time Machine Backup.
You have now set up your System and your important data and programs are played back. The advantage compared to a normal Update is that you won't have to deal with the Legacy of a past Installation.
In a further practical tip we show you how to get the volume under Mountain Lion, a fine set.
