When I insert my Transcend 64GB thumb drive & Western Dig 4TB USB HDD to my teen kid's
Macbook Pro running OSX 10.11.6, both devices are auto-mounted as I can see from Unix
command "df "
However, I can't copy files into the Western Digital USB HDD (it's partitioned into 2x 2TB)
though I could copy files into the thumb drive. Both USB devices are formatted as NTFS.
Can't recall the error message that I got but I can test it out again in 3 hrs time.
What's the reason & how can I fix it such that I could copy to the WD HDD?
Basically I just issue the Unix "cp " or "mv " to copy files from the MAC to the /mount
names of the USB devices.