While installing Mac OS Lion via Apple’s App Store is easy, reinstalling Lion on a clean hard drive is not. A new installation requires access to the App Store (or at least a Internet connection). So if your hard drive just died you are really in trouble. This is where a (home made) bootable Lion partition on a USB stick (8GB) comes as a real life saver. Here is how you create it: 1/ Locate the Lion installer package after downloading it from the App Store (before actually installing Lion). 2/ Right-click and open “Show Package Contents”. 3/ Look for the folder “ShareSupport” and locate the file “InstallESD.dmg”. 4/ Copy (don’t move) that file to another location and open Disk Utility or Carbon Copy Cloner. 5/ Using Disk Utility select “InstallESD.dmg” and do a “Restore” onto your freshly Mac formatted USB stick. (Remember to use that stick as a Lion boot disk only!) You now have a backup Lion system on your stick.