Installing Mac OS X on a Flash Drive

Nearly everybody today uses various kinds of flash storage: USB dongles, memory cards, compact external hard drives. These products are rather affordable, and flash media reached 4-8 GB capacitites long ago. So why not install a fully-featured (but lite) version of Mac OS X on such a drive with a minimal set of applications and files? Many Mac users would like this idea, especially those who often work on different computers and want to do that in their personal environments. So, let's see how you can install Mac OS X this way.

Since we've had a 2GB Kingston SD card and a card reader at hand, we decided to use those in this experiment. But you can naturally use other USB dongles, memory cards, and external hard drives. For installation we used an Intel-based Mac machine, because we did not have an old PowerPC at hand (besides, it would be harder to install with the latter). And don't forget that you won't be able to run an Intel system on a PowerPC and vice versa.

A few words about memory capacity. Having installed Mac OS X, we had about 400MB of free space left on the memory card, so you wouldn't be able to use a 1GB card here. Besides, 400MB is probably not enough to install even a minimum set of applications, to say nothing of any additions. We've installed nearly a naked system (even without Safari and Mail), so it will be up to you to decide what software you need. So, while 2GB is enough to demonstrate the installation process, you will need a larger-capacity card to install a system to actually work with (at least a 4GB card.)

OK, let's get started. First of all, format your flash card. Open Disk Utility, choose the storage drive, Erase tab, Mac OS Extended (Journaled) format, enter any name you like (we typed "MacLife"), uncheck the "Install Mac OS 9 Disk Driver" checkbox, and click Erase.

When formatting is complete, select the card in Disk Utility. You may see the "Owners Enabled: No" line that has to be corrected. Open Terminal, enter the following (don't forget to replace "MacLife" with your drive name):

Then enter your password and see the result in the Disk Utility: "Owners Enabled: Yes". Excellent.

A fully-fledged Mac OS X occupies much space, so we are going to install only the critical system components. What else to install will be up to you to decide. You can do it with a convenient Pacifist utility (available here, 1.3 MB).

This utility is really useful, it might come in handy in many situations (e.g., when you need to reinstall an application from the installation disc without reinstalling the entire operating system.) OK, download it, mount, move to Applications, and run. Now insert the Mac OS X installation disc your PC is bundled with.

After Pacifist recognizes the disc, choose "Open Apple Install Packages" and then choose the first installation disc. While analyzing, Pacifist might ask for the second disc, but you just skip it, since all necessary installation files are stored on the first. When analysis is complete (might take a couple of minutes), you will see a full list of installation packages. You should choose only two packages here: Contents of BaseSystem.pkg and Contents of Essentials.pkg from Contents of OSInstall.mpkg -> Contents of EssentialSystemSoftware -> Contents of EssentialSystemSoftwareGroup.

Of course, if you know exactly what system components you need, you may select them as well. Just don't forget about the capacity of your storage drive. When you have finished selecting necessary components, choose File -> Install Files to Other Disk..., specify your flash drive, and press Install. Now you have about 10-15 minutes to relax, while it's installing.

When the installation process is complete, you might want to remove fonts you don't need from System/Library/Fonts to free up some space.

Besides, we haven't installed Setup Assistant, which may help you install programs. Using Finder copy it from System/Library/CoreServices (in the root folder, not in the home folder) to a corresponding folder on your flash drive (authorization required). You will also need BaseSystem.pkg and Essentials.pkg. Copy those from the /Library/Receipts in the HDD root to the respective folder on your flash drive.

As you all know, Mac OS X boots only from FireWire storage drives. But can be easily bypassed by executing the following in Terminal (no line breaks):

So, we have just copied the files. Now to modify permissions. In Disk Utility choose the storage drive and click "Repair Disk Permissions".

That's actually all. Now you might want to make sure your drive is listed in System Preferences -> Startup Disk (select it there to boot from it every time).

Now reboot with Alt key pressed down. Select the storage drive from the list of options and prepare your Mac OS X (specify user name, password, fill in forms, select time zone and layout - these steps are familiar to all Mac users).

When you boot up your freshly installed operating system, don't be surprised to see question marks in the Dock. As you remember, we haven't installed some applications. Now you should only configure the system, Internet connection, install your applications, and copy your files.

The screenshot above shows the contents of Applications folder right after the installation.