A few months back I wrote about some of the issues I was having with using FAT32-formatted disks for data transfer between Windows, Mac OS X (and Linux) PCs, because although FAT32 supports file systems up to 2TB in size, the format utilities within Windows support a maximum partition size of 32GB and FAT32 only supports files up to 4GB (which doesn’t sound like an issue until you start copying .ISO DVD images and digital video files around).
Even though I use MacDrive for reading OS X disks on Windows XP, I still find it useful to have a FAT32 disk to back up the VMware Server virtual machine which I use to run Windows XP on a Linux notebook PC for my daily work. I did find a great utility a few weeks back for reading ext3 disks on Windows (I think it was Explore2fs), but it’s the universal acceptance of FAT32 that makes it so easy to use everywhere. The trouble is that my virtual machine is about 31GB in size and growing – consequently I needed to create a partition larger than 32GB.
In my original post, I mentioned that FAT32 volumes in excess of 32Gb can be created – Windows is able to read or write larger volumes it just can’t create them natively (the workaround is to use another operating system or third-party tools). In my case, I used the Mac OS X Disk Utility – the important point is to ensure that the disk options are set to use as master boot record (not a GUID partition table or an Apple partition map) after which MS-DOS File System becomes available as a formatting option, allowing me to create a FAT32 disk which filled my entire 55.89GB disk – plenty of room for my virtual machine files and more.
There’s a tool for formatting partitions larger than 32GB in windows: More than 32GB with FAT32.
I had always thought that the XP limit was 32GB (not just a format limit) until I discovered something rather cool. I installed Ubuntu on the same drive, and when it ran it’s partition manager program (forget the name), I inadvertently repartitioned a FAT32 volume to > 32GB. It didn’t even occur to me at the time. Then today I got scared because I realized when I was looking at the drive specs in linux that it was > 32GB. So I searched MSFT’s site, and lo and behold XP does support > 32GB – it just can’t format ’em. Fine! SO the bottom line is that anyone can boot a linux livecd or rescue disk or whatever, and partition and format very large FAT32 filesystems. Sweet!