Macintosh Troubleshooting

Make a bootable Mac OS X USB flash drive for repairs



I am always on the go working on a variety of Macs. As reliable Macs can have their bad days and you don’t want to be caught unprepared. We have all been there, and it only takes that one time faced with a repair not having the right utilities or maintenance tools. I always have a USB flash drive with me that is ready for all situations that require me to diagnose, repair or maintain Mac OS X.

The best device I have in my arsenal of repair equipment is my Iron Key USB flash drive loaded with a bootable copy of MAC OS X. With this clean installed system you can pin point most problems that the main drive might have troubles isolating. I tend to have 3 or 4 of these USB keys, one for each Mac OS (10.4, 10.5 and 10.6). I used to lug around a big bulky portable drive but with more reliable USB flash drives available portability has become a great added tool.




Getting Started
To start you will need to have a USB based Mac, either Intel or PowerPC based on what you plan on repairing and at least a 16GB USB flash drive, I use the a S200 16BG Ironkey from Amazon. SanDisk also carries a reliable drive. Lastly you will need a version of Mac OS X.

  1. Plug in your USB flash drive to your Mac.
  2. Open Disk Utility (Applications > Utilities)
  3. Select your flash drive in the list on the left.
  4. Click on the Partition tab and select “1 Partition” from the Volume Scheme drop-down menu.
  5. Enter a name for your USB flash drive (I called mine “Lifesavor OS X”)
  6. Under Format select “Mac OS Extended (Journaled)”. Make sure the size is somewhere around +/- 16GB.
  7. Below the partition display click the ‘Options’ button.
  8. Choose “GUID Partition Table” from the popup window and click OK.
  9. With you setting chosen click the ‘Apply’ button. Disk Utility will take a minute or two to complete this task.
  10. Insert your Mac OS X installation disc.
  11. Double-click the ‘Install Mac OS X’ icon and progress through the installer until you get to the screen that says “Mac OS X will be install on…”
  12. Click the ‘Show All Disks’ button and select your USB flash drive.
  13. Click on the ‘Customize’ button and a new window will appear.
  14. Un-check all of the items except ‘Essential System Software’. Save space and don’t check ‘Rosetta’ and ‘QuickTime 7’.
  15. Click OK to Install. The rest of the process should be automated and might takes about 30-60 minutes.
  16. Once Installation is complete test the flash drive by booting it up. Restart your Mac and hold down the Option key to choose your flash drive manually. HINT: You will need to do this in the future also to boot to the drive.
  17. After restarting using the USB flash drive follow the set up prompts just like you would a new computer.
  18. Once the OS is running launch Software Update and make sure that your flash drive OS is up-to-date.
  19. Finally install any third party diagnostic utilities you may have. For example, Alsoft’s DiskWarrior is an invaluable tool going beyond what Disk Utility has to offer.


DONE! Although booting to a flash drive is a bit slow it does the job and is convenient; a lot lighter than dragging a book of CD/DVD’s around. Hopefully you will never have to use it but having it available is a great portable emergency too for troubleshooting your Mac.

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2 Responses to “Macintosh Troubleshooting: Make a bootable Mac OS X USB flash drive for repairs”

  1. spacec0w says:

    Hi, thanks for posting this guide. I do some Mac repairs and I was looking into creating a couple external diagnostics drives with multiple partitions for diagnostics, 10.4 and 10.5 on firewire for PPC and 10.4, 10.5, 10.6 on USB for Intel.

    Then I’ve looked at tools such as DasBoot or TechTool Protogo and I’m wondering whether it’s necessary to actually have each version of the OS on a separate partition. Are there any drawbacks to just having one HD be 10.6 Intel and one 10.5 PPC?

    Or, conversely, it looks like at least Protogo lets you boot to just one drive to boot into both Intel and PPC (and I have a USB/FW external hard drive).

    What’s your take on this?

  2. Great Comment! Here is my two cents. Personally I used to tote around some smaller 40/80GB drives ( PPC ) with 10.3, 10.4, 10.5 installed using a WiebeTech Forensic UltraDock. This worked great then. It has been my experience in repairing Mac’s that you don’t need to have two different OS installed for Intel and PPC. All you need are the different OS coupled with your favorite third party repair software. The USB drives work great since they are small and have a large capacity – no bulk. Most Macs have a USB 2.0 port on them so the boot time is not compromised. If you run into a situation where you have a USB 1.0 you might need to switch to a Firewire 400 drive. In my case I still have my WiebeTech Forensic UltraDock.

    As you point out in your case it is safe to assume that you can take the Protogo route and boot the one drive with the OS of your choice for both PPC and Intel. I have to add that I have NEVER tried this using a partitioned drive with different versions of Mac OS X installed. However it stands to chance that based on the old OS X days you should be able to do it – I have just never issued a repair that way. My reasoning for this is that I don’t want to add an unknown variable in my repair path. Hope this helps

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