With the absence of easily obtainable installation media Mac OS X Lion looks like it might make for a difficult clean install. Not so, Apple was hiding the official installation media disc image under our noses the entire time.
- Purchase and download Lion from the Mac App Store on any Lion compatible Mac running Snow Leopard.
- Right click on “Mac OS X Lion” installer and choose the option to “Show Package Contents.”
- Inside the Contents folder that appears you will find a SharedSupport folder and inside the SharedSupport folder you will find the “InstallESD.dmg.” This is the Lion boot disc image we have all been waiting for.
- Copy “InstallESD.dmg” to another folder like the Desktop.
- Launch Disk Utility and click the burn button.
- Select the copied “InstallESD.dmg” as the image to burn, insert a standard sized 4.7 GB DVD, and wait for your new Lion Boot Disc to come out toasty hot.
It is important that you burn your Lion boot disc or backup the Lion installer prior to installing Lion itself. If left in the Applications folder the installer will be removed after the Lion installation is completed. If you are reading this article after upgrading to Lion all is not lost. A fresh copy of the Lion installer can always be re downloaded from the Mac App Store by clicking on the Purchased tab with the Option key held down.
With the Lion boot disc you can boot any Lion compatible Mac, and install 10.7 just like you installed previous versions of Mac OS X. You can even use Disk Utility’s Restore function to image your Lion boot disc image onto a external drive suitable for performing a clean install on a computer without an optical drive. Clean installs with Lion are easy once you find where Apple has hidden the secret boot disk.