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I avoid write caching like the plague. My first experience with it was with pre-Windows DOS 4, the thankfully short-lived version between 3 and 5 (HD volumes larger than 32 MB). MS added disk caching to DOS 4 and enabled write caching by default, without bringing it to users' attention.
 
Unbeknownst to me, my boss' 17-year old son, who was hanging around the office all summer (this is Motorola by the way, not some small operation), was put to work by a couple of my engineers doing some dirty work that they were too lazy to do (configuring new PCs for customers). He installed DOS 4 instead of the tested and approved DOS 3. These PCs were running real-time SCADA control system software with large databases.
 
Then the calls started coming in about corrupted databases. It took some time and plenty of aggravation to figure out that it was an OS issue, that the PCs had DOS 4 installed instead of 3, and then all of the time it took to figure out what Mickeysoft had done. Really p'ed off some important customers.
 
I called it the Itamar virus (the little s**t's name).
 
Write caching writes to RAM. It then needs to be written to disk. If ANYTHING interrupts that process, your destination file is corrupted. Trust me on this...there are a LOT of things that can AND do interrupt that process.
 
My recommendation? AVOID.

I would recommend using Robocopy.
It stands for 'Robust Copy'.
It has a ton of parameters, but the essential ones are like this example from a script I use to backup my VST stuff:
 

@echo off
echo Copy new files from all VST locations: Kore, Hosts, VST-32, VST-64, VST3 to Flash (M:)?
pause
robocopy "C:\Program Files (x86)\Common Files\Native Instruments\Kore 2\PlugIns" "M:\VST Plug-ins\Kore plugins\PlugIns" /E /SL /NP /NDL
robocopy "C:\Program Files\Common Files\Native Instruments\Kore 2\PlugIns64" "M:\VST Plug-ins\Kore plugins\PlugIns64" /E /SL /NP /NDL
robocopy "G:\VST Host" "M:\VST Plug-ins\VST Host" /E /SL /NP /NDL
robocopy "G:\VST-32" "M:\VST Plug-ins\VST-32" /E /SL /NP /NDL
robocopy "G:\VST-64" "M:\VST Plug-ins\VST-64" /E /SL /NP /NDL
robocopy "C:\Program Files\Common Files\VST3" "M:\VST Plug-ins\VST3" /E /SL /NP /NDL
echo All done!
echo ---------
echo.

 

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USB may have timeout issues, sleep issues, low power issues, hub issues, etc.
 
Using a port closest to the controller with power management turned off on the hub would help.
 
Some copy methods which know the full size of the files might allocate that size first to be sure that space is available as the copy proceeds.
 
There are many other ways to make reliable copies - you can make an archive with no compression that has some sort of CRC code to be sure the extraction is exact. You can use a tool like Acronis to backup and verify files.
 
When I want the most reliable means of verifying my backup data, I use a set of scripts I made using md5deep.
It makes hashes of files on drives or folders and lets me see if the data is still unchanged at a later date.
Drives have a 10**-14 error rate, small, but finite. That's about 1 error every 10 Terabytes, I think.
 
If you are handy with Windows shell scripts you can modify these to suit yourself, just give me a PM or email.
 
 

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