Installing a new operating system over the old one can create problems with stability. Apple disregarded these concerns with the release of Mac OS X 10.7 Lion by only allowing the initial release in the Mac App Store for download. A USB Flash drive version will become available in the future, but there is a way to get a clean install from a DVD or USB Flash Drive now with some effort.
We will show you how to create your own installation DVD or USB Flash Drive. For now those are your only two options since Macs won’t boot from an SD card. In the case of the Flash Drive we will also show you how to put two partitions on one 8GB or larger flash drive so that you will also have all your Mac apps on the drive ready to install after you install the OS.
Why Make an Install Disk
Why would someone want to create an install disk instead of install Lion on top of their old OS X installation the way Apple wants? While it seems to work well in our experience, here are a few reasons to go through the trouble:
- Clean install of an OS is usually more stable
- Forces user to clear out old file and app clutter that is not used anymore saving drive space
- A future hard drive crash might leave you unable to install from the Mac App Store or the new Lion Recovery feature
- Your are a geek and trying technical stuff on a computer is fun
While the first two and last option are good reasons, the third is the most important. This is a backup plan so you don’t have to take your computer to Apple to fix it if the hard drive or SSD drive won’t boot anymore. A clean install usually fixes these kinds of problems.
What You Need
In order to do this you will need the OS X Lion installation file. If you already upgraded to Lion the install image is deleted by default and it is already too late. Some other sites have posted that you can re-download the file. But the only way to do that is on a system that doesn’t already have Lion installed. The only way to do this is to use your computer’s restore disk to reinstall Snow Leopard or an earlier version of OS X. Do this before you install Lion but after you download it from the Mac App Store.
You will need a USB flash drive of at least 5GB. We tried this with a 4GB drive and Disk Utility would not burn the Lion install image saying it was too small.
We chose a 16GB drive instead and created two partitions on it, one for Lion and one for our downloaded, non-Mac App Store apps. That way you have a single disk to restore your OS and your apps. Back those app files up though in case you lose your flash drive.
How to Create the Disk
- Download Lion from the Mac App Store but don’t install it yet
- Open the Applications folder and right-click on the Lion installer
- Click Show Package Contents and find the InstallESD.dmg image file in the Contents, SharedSupport folder
- Open Disk Utility in OS X and insert your Flash drive
- Either open the image file from the File menu or drag it from a Finder window into the Disk Utility’s left hand column
- For DVD insert your DVD and select the disk image and click the Burn button and when it is finished skip to step 16
- For Flash Drive click on the drive listed in the left hand column of Disk Utility and select the Partition tab
- For 2 partitions like we did, then under Partition Layout: choose 2 Partitions
- For 1 partition making the whole USB drive an install dive under Partition Layout: choose 1 Partition
- If you want two partitions, then below the Partition Layout drop down is a visual representation of your layout – drag the slider up or down till it shows about 5GB or enter it manually in the Size box to the right – note: the Lion image file is about 4GB but needs room to expand
- Give each partition a name and choose Mac OS Extended (Journaled)
- Click Apply
- After previous step finished choose the Restore tab and in the Source box drag the Lion install image from the left hand window
- Drag the USB partition you set up in step 9 to the Destination box and click Restore to make it burn the Lion image
- When complete put all the app files you want to install on the non-Lion install partition of the flash disk
- Insert the Flash Drive or DVD drive into the Mac you wish to install Lion on
- Boot the machine holding down the option key
- Choose Mac OS X Install ESD from the optional disk to boot from when they appear – note the end of the disk name is cut off on some monitors
- Follow the installation instructions on-screen
- Reboot when it is finished and now you can install your apps from the Flash Drive if you created one
Be sure to save this USB drive and as we said before make sure you have a backup of the downloaded apps on the second partition, if you go that route.