Using FAT 32 with Mac OS X

Conventional wisdom holds that one of FAT 32's classical limitations is a 4 Gigabyte files size limit. I've done a few searches on the net, and I find this rule repeated ad-infinitem, without contradiction.

I recently purchased a 320 GB Iomega Prestige external drive that I plan to use interchangeably with my Mac and PC systems. To do this, I re-formatted the disk to a single 320 GB partition with FAT 32 file system (The drive comes formatted NTFS).

Yeah, I know there are work-arounds that would permit me to format it NTFS, and use it read-write on my Mac, and there are probably a few solutions that would permit me to format it Mac OS Extended, and use it my PC. I prefer not to use any "workarounds".

Here's my question.... I had occasion to copy a few files to the drive from my MacBook to the drive, namely my Virtual Machine files, that I don't want to use Time Machine for. I had no problem doing so. The two files exceed 4 Gigabytes handily, with one of them being over 30 Gigabytes! Oops, this can't be done, right?

I ask, how is this possible? I thought I had a 4 Gigabyte limit with FAT 32. Does the fact that I formatted the drive with my Mac give me some sort of advantage that Microsoft's formatting using the same file system does not?

I have read that the reason the FAT 32 files sytem can't store files over 4 Gigabytes, is the insufficient lack of storage within the allocation table for the requisite number of pointers required for a file over 4 Gig in size.

Can anyone provide a real explanation? I had heard that the 4 GB limitation is a limit of OS's, and not FAT (kinda like the 32 GB limitation FAT 32 partitions). But then this would contradict the theory that it is an insufficient file pointers dilemma, right?

 

just virtual machine files? yeah they often look like a singe file, but are stored in smaller files by default... most will split virtual machines up into 2gb files for the file system...

if its nothing to do with that, you have something else weird going on... or it lost parts of the file and just makes you think its working.

 

Also, the reason that FAT32 is limited to 4GB file sizes is not because of pointers. It's because the file allocation table (FAT) uses 4 bytes (32 bits) to store the size of files.