I recently connected an exteral USB 3.0 drive and have had problems creating PGP volumes on it. The first time, the volume was created but not mounted. Manual attempts to mount it failed. Then looking at the PGP Desktop screen I notice the reporte size was off the charts. The physical size asked for and created was 1024G. Next I tried again dropping the size down to 1000G. This time I got the message below.
I created a 100mb volume successfully as a test. Not sure if it's a timing issue with the USB 3 card (given the randomness of the failures) or if AF drives just should not be used to hold PGP 'volumes'.
I confirmed it as an AF drive using fsutil.
Bytes Per Sector : 512
Bytes Per Physical Sector : 4096
My laptop has a drive with the same characteristics and a 20mb volume that has never caused any problem.