User profile for user: PatrickB
PatrickB Author
User level: Level 1
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Disk Utility won't let me format external drive to FAT32

Maybe this cannot be done or the answer is simple and I am missing it. I have a 1.5tb Maxtor drive hooked up via fw800. I want to have 120gb of this as Mac OS extended journaled to back up my internal drive via Time Machine. I want the other 1.38tb to be in FAT32 so I can share files between my windows and mac machines. I keep all of my external storage except for the backup partition in FAT32. I have never had an issue until I upgrades to Leopard and now when I click on the larger partition I only have the option for the 4 mac formats-- FAT32 is not available. I can format the entire 1.5tb to FAT32 but once I try and partition it only mac formats are available. I forgot to mention I just did the upgrade to 10.5.1 and the issue is still present.

How do I format the smaller partition as mac os extended journaled and the larger as FAT32? Any help is appreciated.

Thanks so much,
Patrick

PS. I did a search but did not find anything.

Message was edited by: PatrickB

Posted on Nov 15, 2007 11:38 PM

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5 replies
User profile for user: BobZune
BobZune
User level: Level 2
245 points

Nov 16, 2007 3:04 AM in response to PatrickB

It may depend on the type of partition table scheme you are using (see bottom of page in disk utility for that says Apple Partition Map/APM, GUID Partition table/GPT or Master Boot Record/MBR partition map).

MS-Windows can read MBR scheme only (64 bit MS-Windows supports GPT, according to MS). If you have Apple Partition Map, your disk won't be usable on Windows. I suspect you have APM partition table and hence the disk utility is not giving the option for FAT32 format, since you can't use it under MS-Windows.

On the Mac side, all 3 schemes are readable (for bootability, you'll need APM on PPC Macs, GPT for Intel Macs). Time Machine doesn't need a bootable disk, but I'd suggest APM/GPT if you are using PPC/Intel macs respectively (but I'd think either will work for Time Machine, if you have a mix of Macs).

But here's the catch - Apple says Time Machine won't work with drives with MBR partition map (even though Macs are MBR-aware), so the issue for you is Time Machine's ability to use MBR drives. http://docs.info.apple.com/article.html?artnum=306932

I suspect unless you are on an Intel Macs (OS X) and use only 64 bit MS-Windows (using GPT)/Itanium, using the same disk for TM and FAT32 sharing between Mac and Win worlds is not possible. Not the desirable answer.

If you do want to experiment, make a temporary setup and try it out on both Mac side and Windows side first (on all your machines), before making a "production" system. You can select the DISK (first line on Disk Utility for that disk, not second line) and click on Options at the left bottom (it might have to be erased first) and then select the type of partition scheme. Note formats like HFS+/FAT32 are a level lower in the hierarchy than partition map/table.

Let us know what you find out/decide?
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User profile for user: PatrickB
PatrickB Author
User level: Level 1
0 points

Nov 16, 2007 1:18 PM in response to BobZune

Thanks, Bob, that is exactly the information I needed. I did indeed have a APM partition scheme in place. The computers I am most likely to use are Intel Macs and Vista PCs. Also, I will probably never boot from this drive. The solution I chose was to use GPT and then I was able to format correctly. I think this is the best solution for my situation.

Thank you again for your quick and helpful reply,
Patrick
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Disk Utility won't let me format external drive to FAT32

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