Macbook Pro could copy files into thumbdrive but not to a 4TB WD USB HDD

sunhux used Ask the Experts™
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.
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I'm sure the WD HDD is not write-protected because I could
copy files to it from my Thinkpads
David FavorFractional CTO
Distinguished Expert 2018

Depends on how you have your WD 4TB drive connected.

Most first generation external docks could only access 2TB drives + if you inserted a > 2TB drive, each disk type (vendor/size) would act differently.

Provide the vendor + part number of the enclosure/dock device you're using.

This will show how large a device you can access.

Tip: Macs don't speak NTFS natively. You'll require external software, like Microsoft NTFS for Mac by Paragon Software or something similar.

The software you're using to do your NTFS formatting may require updating also.
Sales Representative
You're sure the thumb drive is formatted ntfs? Macs natively don't write to the ntfs disk without some form of third party software (like paragon). OS X will read ntfs without problem, but writing to ntfs is a whole other issue. If you're looking to transport files from Mac to pc formatting the drive as ex-fat is useful
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Most Valuable Expert 2013
MacOS natively reads NTFS but doesn't write to it so "you can look but you can't touch" :)
You really need them formatted to sometihng both OS's can read/write to or add tools to the Mac as Speed54 suggests.

As an external 4GB drive it's probably formatted GPT to make the most of the available capacity.
David FavorFractional CTO
Distinguished Expert 2018

As Speed54 suggests, stick with EX-FAT for easy file transfer between OSX + Windows.


David, no docking used.

I check the thumb drv if its exFat
noxchoIT Product Manager
Top Expert 2009

Get yourself a NTFSforMacOSX driver and have writte access to any NTFS formatted drive:
No need to change formats then.
Seagate external drives comes with a free Paragon NTFS software just for Seagate external NTFS disks.

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