Make Your Own Mac OS X Lion USB Installer

Currently you can buy OS X Lion on a USB Thumb Drive for $69 or you can buy OS X from the app store for $29 but maybe you want a backup of that install. Here are instructions on how to purchase OS X Lion from the App Store and then make a 8GB USB drive a Mac OS X Lion USB Install drive.

1. After downloading Lion DO NOT CLICK the INSTALL button (the installer deletes itself automatically when it finishes installing Lion.)
   
2. First, go to your Applications folder, right click on Mac Os X Lion Install application and select Duplicate.
   
3. Move the Copy to your Downloads folder.
   
4. Get a USB flash drive that is at least 8 GBs. Prep this flash drive as follows:
   
   • Open Disk Utility in your Utilities folder.
     
   • After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area. If it does not say "Verified" then the drive is failing or has failed and will need replacing. SMART info will not be reported on external drives. Otherwise, click on the Partition tab in the DU main window.
     
   • Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
     
   • Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
     
   • Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
     
   • Click on the Erase button. The format process can take up to several hours depending upon the drive size.
     

   [*]Locate the saved Lion installer in your Downloads folder. CTRL- or RIGHT-click on the installer and select Show Package Contents from the contextual menu.

   [*]Double-click on the Contents folder to open it.

   [*]Double-click on the SharedSupport folder. In this folder you will see a disc image named InstallESD.dmg.

   [*]Plug in your freshly prepared USB flash drive. You are going to clone the InstallESD.dmg disc image to the flash drive as follows:

   
   

   • Open Disk Utility.
     
   • Select the USB flash drive from the left side list.
     
   • Click on the Restore tab in the DU main window.
     
   • Check the box labeled Erase destination.
     
   • Select the USB flash drive volume from the left side list and drag it to the Destination entry field.
     
   • Drag the InstallESD.dmg disc image file into the Source entry field.
     
   • Double-check you got it right, then click on the Restore button.
     

   [*]When the clone is completed you have a fully bootable Lion installer that you can use without having to re-download Lion.

   
   

NOTE: If you have InstallESD.dmg then that was the file in the SharedSupport folder. There is no such folder in the InstallESD.dmg because that is the disc image you clone to the USB drive per the above instructions.