I did some extensive testing of the USB 3.0 speed about a year and a half ago, from a 4TB WD Cloud to a 4TB WD USB My Book as well as from the Cloud to a Vantec USB Raid enclosure via a gigabit ethernet.
Now to be fair, you cannot quote small file copying speeds as the overhead of copying files like jpegs, mp3s’, epubs etc are attrocious even if you are copying directly from computer to a USB 3.0 connected drive. Your first dozen files may get the 140MB/s speeds but once the buffer is filled everything slows down to about 4 to 6 MB/s and all this has to do with sector allocations, blocksizes, directory allocation and so on.
Thus you will always get a speed hit when copying photos, musics and ebooks which is essentially what we store these days anyways so complaining about them applies to every device, not just WD.
So to get a valid speed, you should always test the speed on a large movie file, something in the neighborhood of 800MB and up.
Now you should also make sure that your scanning services are turned off, those are the media scan services that keeps popping up once it has detected that you have copied a photo or a movie and takes up to 100% of your cpu thus reducing your copying speed.
Through the USB 3.0 port on the Cloud, the last time I checked (1.5 year ago), WD maxes out at 40MB/s when copying from a WD Cloud to a WD My Book (NTFS format). The funny thing is this is the max speed you get from copying an 800MB file from your computer to the Cloud, thus the max speed might be indicative of MAX cpu software speeds rather than maxed network or USB 3.0 port speeds.
At that time when I saw this 40MB/s, I thought that WD simply capped it to 40MB/s since that was the max speed when writting from a computer to the Cloud but as I write this post up today, I think it is just the max speed of the CPU for passing through data.
The other funny thing was when I tested the Vantec Raid drive using striped 0, which gave speeds of up to 160MB/s when connected directly to a USB 3.0 port on the computer, the max speed of the Cloub USB 3.0 was 30MB/s, leading my suspicions to code like…
if WD drive attach
set maxspeed to 40MB/S
else (for every other generic drives)
set maxspeed to 30MB/s
Reading from the Cloud always gives me about 80MB/s read speeds and 70-75MB/s from the attached WD My Book. The write speed for the attached My Book is 35MB/s
My Cloud to a computer
MyBook to a computer from My Cloud
MyCloud to the My Book
Computer to My Book
MyCloud to a Vantec Raid Stripe 0 Raid
Computer to the Vantec Raid Stripe 0 Raid
Computer to a $300 router that had a USB 3.0 port
These values are as a close as I can remember from a year and a half ago. When I tested them for the speeds I had needed a simple NAS that could give me the minimum of 40MB/s writes which is really the average NAS speeds for even a computer to computer NAS. Although you can get faster NAS you end up paying for the speeds and there is no need for that type of speed for an archival unit since once you copy your files over, you don’t do it over and over again.
Your testing should be in the neighborhood of these values and if not, talk to WD.