I used the Theseus bi-directional USB copy module to copy many large files from an NTFS-formatted external hard drive. This worked well except all the resulting folders and files (that end up in "usbcopy/sdf1") were read-only so I couldn't move or delete anything there. Note that this method copies everything on the external drive.
After several false starts, I installed the SSHD and SYSUSER modules and used PuTTY to log into the n5200 as "sys". At that point I was able to use a standard Lynux command to change permissions. This let me move/delete the sdf1 files from windows. I believe the Linux command was:
chmod -R ug=rwx /raid/data/usbcopy/sdf1/
Note the capital "R" (recursive) which applies the new permissions to all files and folders in sdf1.