How to partition an external hard drive for use with OS X and Windows, and booting OS X too?

May 12, 2006 12:10 AM

I need help using my external USB hard drive with Mac OS X, and there's

more inside. You see, I have this 200GB USB hard drive, currently formatted as a single FAT32 partition. I'd been using it with my Windows XP desktop. Now I have a MacBook Pro and I need help figuring this out. The MacBook is named Olivia and the Windows machine is named Snowball. The FAT32 volume is named Torquemada.

Is there some partitioning scheme that will let me have Torquemada in "GUID partition table" mode* so I can have a bootable OS X image on 80 GB of it, and at the same time have the other 120 GB be FAT32, and therefore useful for moving files between Olivia and Snowball? Or does the one preclude coexistence with the other?

If I have my OS X install DVDs, and I have a Torquemada formatted to boot OS X, how do I actually get a bootable OS X on there? Once that's in place, say I wanted to boot Olivia off Torquemada instead of her internal drive, what key do I hold down to tell her so?

*whatever that means.

posted by evariste to Technology (2 answers total)

Best answer: Using Disk Utility, you should be able to make an 80 gig HFS+ partition, and a 120gb FAT 32 partition. If disk utility doesn't let you format to FAT32 then leave it unformated, and do the formatting in windows (using fdisk or whatever is in vogue at moment). The OS X DVD you have should let you install Mac OS X onto the external hard drive.

You can boot up off the external by picking it as the start up disk from the start-up disk preference pane. When the system is starting up, Option-Command-Shift-Delete, is the keyboard shortcut to tell the computer to ignore the internal HD and look for OS X elsewhere.
posted by chunking express at 7:37 AM on May 12, 2006

If the earlier suggestion doesn't work out for you, take a look at this macosxhints.com article and its comments.
posted by Mike C. at 2:48 PM on May 14, 2006