After running my first ever (mirror)fbackup, most (but not all) folders residing on my external drives were empty in the destination location. The huge backup log was to big to be opened by notepad, but wordpad opened it properly. Hundereds of "network path not found" references, even though my external drives are directly plugged in to my computer (through a USB hub).
On the backup of an external USB disk drive most but not all of the folders were empty, those that were not, weren't anywhere close to complete.
On the backup of an external USB Flash drive, all folders were completely empty, though loose files (not in folders) copied properly.
Thanks to all for any insights that can be given.