What does reformatting a USB drive really do?

[QuantumSpin]

VirtualBox 4.3.0 with Extensions
Host: Linux Mint 16 Cinnamon
Guest: Windows XP Pro SP3 with ExFat patch
External USB Hard Drive: 1TB, USB3, with 500GB NTFS partition.

I wanted to reformat the 500GB NTFS partition on my external USB drive to ExFAT so that it can be read and written to by my Mac (without needing to buy additonal NTFS software). And I know that if you format a drive with ExFat from a Mac it can't be read by Windows but it works fine the other way around (format ExFat using Windows and both OS's are happy) so I attempted to format the partition using XP and it appeared to work fine, but when I exiting the guest OS the drive was still NTFS when viewed from Linux. When I'm in XP it appears to be ExFAT and empty, but in Linux it's still NTFS and all the original files are still there. What really happened?

[socratis]

I know that if you format a drive with ExFat from a Mac it can't be read by Windows

The above statement is not correct. I have an ExFAT USB stick right here. It was formatted in my OSX 10.6.8 and it can be read by all Win machines (that can actually read it). I'm not sure what happened with your original topic.

[mpack]

When I'm in XP it appears to be ExFAT and empty, but in Linux it's still NTFS and all the original files are still there. What really happened?

Sounds like you're using a virtual drive, which is the normal case in a VM. The other possibilities don't bear thinking about.

[QuantumSpin]

thanks for the reply socratis. I'm curious, when you formatted your drive ExFat in Mac OS, did you select MBR or GPT? And did you test the drive on any 32-bit Windows OS's that weren't running virtual? I believe I accidently selected GPT (the default?) and if I'm understanding Microsoft's FAQ page correctly (google Microsoft MSDN gg463525), 32-bit Windows OS's are unable to read GPT drives. Regardless, I should have been clearer in my initial post.

[socratis]

MBR. Support for XP > SP2 is enabled with Microsoft's KB955704 article.