01-25-2010, 10:51 AM

I did a quick search and didn't see anything come up immediately but I really need this issue resolved as quickly as possible.

I have dozens of USB flash drives all formatted as FAT using Mac disk utility on 10.6.2 but Windows users are reporting that the drives come up with a warning that says it has to be reformatted and that only 200 mb are available (each drive is 8 GB in size so it shouldn't be this way)

Any ideas as to why it mounts fine in Mac and Windows users are having this issue?

I need the drives to work on Mac and Windows and figured FAT was the way to go but so far no go and I don't want to have to reformat them all on a Windows computer just to make sure they work properly. That would defeat having a Mac Pro for work.

01-25-2010, 05:33 PM

I would like an answer to this as well. I have a 4gb usb stick doing that exact thing right now.

01-25-2010, 08:40 PM

Guys....

This has been banged around many times, but here it is again:

You CAN NOT use Disk Utility to format a flash drive and then use it in a Windows computer. Here's why: Disk Utility creates a 200 MB protective partition in front of the main partition. Mac OS X ignores this 200 MB partition and will "see" the entire flash drive as one partition.

HOWEVER.... Windows "sees" the flash drive as removable media and as such will only recognize the first partition it sees. And guess what that first partition is? Yes, the 200 MB.

Solution: Reformat the flash drive using "GParted" (Linux utility). That will wipe the flash drive clean and setup one true partition. GParted is a free download from here.

Regards.

01-26-2010, 07:35 AM

Or just format the flash drive on a Windows PC as FAT to used on both OS's.

01-26-2010, 05:11 PM

Originally Posted by JUKE179r

Or just format the flash drive on a Windows PC as FAT to used on both OS's.

You can't. As I stated above, Windows will "see" it as a 200 MB drive and will only format that portion of the drive. Remember - it's removable media. Kind of a "catch 22". That's why I recommend using GParted.

Regards.

01-31-2010, 06:13 AM

So basically don't format a thumb drive in a Mac if you are going to use it in aboth PC and a Mac? That's wierd.

01-31-2010, 06:19 AM

Originally Posted by JUKE179r

So basically don't format a thumb drive in a Mac if you are going to use it in aboth PC and a Mac? That's wierd.

read chscag's first post .. it IS possible, just not with Disk Utility

01-31-2010, 07:05 AM

My bad... I meant that it's wierd about not being able to use Disk Utility being that you have to use a 3rd party program just to use format a thumb drive to be seen in both OS'.

05-10-2010, 05:50 AM

Facing the very same problem, I found out that it CAN be solved with Disk Utility after all: instead of formatting/erasing the flash drive, just choose the partitioning tab, select "1 partition", "MS-DOS (FAT)", and under "Options" "MBR (Master Boot Record)". This should result in a volume that can be mounted both on Windows machines and Macs without any problem.

05-10-2010, 06:24 AM

Just to toss this out there as well, make sure that you properly eject the drive from Mac. I have seen a few drives trashed because people just pull them out without unmounting the drive.