Wednesday, 20 March 2013

RMPrepUSB - FAT32 bug found!

I found a funny issue with what I thought was caused by grub4dos today, but it turned out to be an issue with the way RMPrepUSB formats a FAT32 volume!

I noticed that if I copied more than 126 or so files to the root of a USB stick prepared using RMPrepUSB as FAT32, then I could not access any file that I added to the USB stick under  grub4dos (even though they were accessible from Windows). At first I thought this was a grub4dos bug, but when I formatted the same USB stick using Windows, it all worked fine.
I also found a fat32formatter.exe utility which also worked fine. The problem was clearly in RMPartUSB (which actually does the formatting). After a few hours, I eventually tracked down the problem.
You can read about the saga here if you want more details.
The bug is fixed in RMPrepUSB 2.1.661. So if you copy lots of files to the root of your grub4dos USB drives that were prepared using RMPrepUSB, you might want to reformat them with the new versions!
The bug has been there since day 1!