Upgrading Mac To Snow Leopard Using USB drive

Jeffry Thurana 05-09-2009

00 SL USBThe latest Mac OS X – version 10.6 – was released to the public on August 28. Mac users who pre-ordered Snow Leopard should already have their copy delivered and surely have upgraded their Mac to Leopard by now. The Mac communities’ discussions are filled with the post installation experiences and thoughts and comments about the latest feline from Apple.


One of the afterthoughts I have with another Mac user friend is about the installation process for Macbook Air which has no optical drive. It was a short discussion closed by a “using Remote Disc of course” statement and a few chuckles. But then I wondered whether it’s possible to install Snow Leopard (or any other version of Mac OS X) using a USB thumb drive (something like creating a portable Ubuntu installation USB How To Create A Portable Ubuntu Installation USB On The Mac Read More that we’ve discussed here before). This would be useful for Mac users who have no access to a physical optical drive.

For the sake of curiosity, I did a little Googling followed by a little experiment.  Less than one and a half hours later, I knew the answer.

Utilizing the Disk Utility

Some readers have pointed out in the Ubuntu article that the whole process of creating a USB installation disk can be done the “GUI-way” using the Disk Utility (Applications/Utilities/Disk, so we’ll try that route in creating our USB installation drive for upgrading your Mac to Leopard.

As the installation DVD is almost 7 GB in size, we’ll need a USB thumb drive with at least that amount of space. I used an 8 GB thumb drive, but larger types or even a USB external drive with an empty partition above 7 GB could also be used.


The first thing to do is to format the drive. Select the drive from the left pane of Disk Utility then click the “Erase” tab. Choose “Mac OS Extended (Journaled)” from the “Format” option, then give a name to the disk and click the “Erase” button.

upgrading mac to leopard

After the formatting process is finished, go to the “Restore” tab to ‘restore’ the content of the installation disc into the USB drive. Select then drag and drop the source image (Snow Leopard) and the destination (the USB drive) from the left pane to the corresponding place. Note: you can choose a disk image from a physical disc, an image file – on the hard drive or web location – as the source.



Then click the “Restore” button to start the process, which will roughly take about half an hour.

upgrading mac to leopard

After the restoring process is finished, we can see that the USB drive has been transformed into an installation disk.

upgrade mac to snow leopard


However, we can’t do the installation by clicking the “Install Mac OS X” logo. You’ll just get the warning sign ‘The application “Install Mac OS X” cannot be used from this volume‘.

05 Warning_Sign

Now, let’s continue with the real deal.

The installation process

Eject the DVD but leave the USB plugged in. Restart the system and press the “Alt” key on the keyboard during restarting. You will have the option to boot from the hard disk or a USB disk; I guess you know which one to choose, right? :)


The whole installation – or upgrade, some would say – process took about 50 minutes. Then you’ll get the thank you window saying that everything’s done.

06 Setup Finish

There are some applications that are still incompatible with Snow Leopard, which is to be expected at the early stage of every new OS. They are moved to the “Incompatible Software” folder in the start up disk. If you’d like to find out who they are, click the “More Info” button.

And I think now is the time to say hello to our new OS.

08 Snow Leopard is here

Related topics: OS X Snow Leopard, USB.

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  1. Steve
    March 14, 2019 at 10:19 am

    Thank you very much

  2. Markus
    January 24, 2010 at 2:30 pm

    hello. if i install this to my mac i dont loose anything? i need to know that before i do it. bekose i have much musik and staffs and i need it but dont have anything to back it up to.

    • Jeffry Thurana
      January 24, 2010 at 3:29 pm

      "Upgrading" process will retain all of your files. HOWEVER, backing up all of your files is always highly advisable.

  3. Ray
    December 14, 2009 at 2:19 pm

    Did you ever proof read this before you published it.

    You start out by titling the article "Snow Leopard". Then you discuss ""upgraded their Mac to Leopard", the "latest feline from Apple". I believe you mean Snow Leopard.

    Then to installing Snow Leopard using a thumb drive "for Mac users who do not have access to a physical optical drive."

    You then provide instructions for installing "upgrading your Mac to Leopard." Since this is an Air discussion, the Air was originally shipped with Leopard. This is a solution for no one. Assume you meant Snow Leopard.

    Then the best, "You'll just get the warning sign 'The application "Install Mac OS X" cannot be used from this volume'. Then, "Eject the DVD but leave the USB plugged in." Of course it can't be used, you are on the computer with the optical, not the Air which is what you want to upgrade. You're also on the computer with an optical drive which is in conflict with the entire premiss of your article.

    For those readers who would like to understand what the author is trying to tell you, go here It will tell you how to do this in less than a page and in an understandable manner. For those of you without an optical, go find a machine with one but remember, that's not the Air you're trying to upgrade.

    • Grammar Dude
      May 11, 2015 at 10:27 pm

      You spelled premise wrong.

  4. Jimmy Bivona
    December 7, 2009 at 12:37 pm

    I put it on my 5 year old iPod which is still running on it's original battery. I sort of planned on holding down the alt key but I don't quite know why. Couldn't hurt, anyway. Ya think?

  5. MacLoving
    October 12, 2009 at 2:32 am

    Awsome Tut...i am installing Snow Leopard as i write this.. :)..i am MAcLoving

  6. sophie
    September 23, 2009 at 8:05 am

    Hey man, great post! Thanks for the tip.

    However, i think this site here might have a simpler method (without the rebooting and all) [Broken Link Removed]

  7. Aaron Srun
    September 12, 2009 at 8:18 pm

    Thanks so much for this article. The part that really helped me was holding down alt at restart, I never realized to do that in the 5 times I tried. I'll try it now and see how it works.

  8. Max
    September 5, 2009 at 2:39 pm

    I liked this article about what OS will be after Snow Leopard.