To check flash drive information on the ConnectPort X4, telnet to the unit, login as root and issue the  "flashdrv" command.  The following is an example with 2 USB flash drives (one 2MB and one 4MB):

#> flashdrv

Volume                     Bytes                    Used             Available              Bad   Use%   Mounted on 

FLASH_USB           4002.94 MB      2414.24 MB       1588.69 MB       0.00 MB     60      A:/        

DISK_IMG             2102.39 MB        857.40 MB       1244.98 MB       0.00 MB     40      B:/        

We recommend avoiding any flash drives with built-in compression or which look like 2 drives.