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first post here

I have currently a USB hub 2.0 with 5 USB 2.0 keys with a batch script to write a specific directory into the USB 2.0 keys (Same stuff on each keys). I have 700 keys to duplicate that way... (maximum theorical speed of USB 2.0 = 480mb/sec). 800mb writes (1 key) on the 5 key takes about 45mins for the process to complete.

I wonder if I put a USB 3.0 hubs with the same USB 2.0 key, would it accelerate the process? Since the hub would have 4000+ mb/s, it would use the maximum bandwidth of EACH usb2.0 keys? or it would run at the same speed of my original solution?

I am aware that if I would take a single USB 2.0 key on a USB 3.0 port, the transfer speed would be the same as a USB2.0 key on a USB 2.0 port.

Sorry about my English.

Just wondering

Best regards,

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No, use of USB 3.0 hubs will not accelerate the write throughput on USB2.0 drives, because the USB 2.0 subsystem is completely independent of USB 3.0. It is in parallel to USB 3.0.

The backward compatibility in 3.0 is different from USB2->USB1.1 compatibility, where it was provided via hardware Transaction Translators to FS and LS modes for each hub or port. There is no such thing as "Transaction Translator" between SS (USB 3.0 speed) and HS (USB 2.0).

However, something is wrong with your setup, and performance calculations. The USB 2.0 can provide up to 30-35MBytes/s of write speed on a good USB 2.0 drive, but typically it could be anywhere from 3MBytes to 12-15MBytes/s. Even if your pen drives have a mediocre 10MBytes/s write perfromance, writing 800MBytes (I asume MBytes, not Mbits) should take about 80 seconds, unless your data consist of thousands of very small files. So 45 minutes for 5 pens is quite a discrepancy from expectations.

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  • The usb flash drives are VERY cheap, costed 2$ / 2GB units from china. I thought that if I used a USB3 HUB, the main USB3 cable from the computer / HUB would give a better bandwidth (not individualy on each key, but on all of them). Example : I can write at a maximum 20MB/s on one USB flash drive, if I copy the same files on 3 usb flash drive, I would have a maximum bandwidth of 60MB/s (maximum theorical speed of USB2). Using 5 flash drive would drop the transfert equaly (kind of) 12MB/s. I thought that a USB3 hub would give each of the 5 keys 20MB/s.
    – rturcotte
    Commented Nov 10, 2016 at 21:21
  • For USB2 devices, USB 3.0 hub does not exists, all traffic goes through an internal USB2 hub that is built into USB3 chip. Maximum theoretical data transfer speed of USB2 interface is 40MBytes/s, 5kB * 8000 u-Frames/s. 5kB is 10 bulk 512-byte packets. Accounting for protocol overhead, possibility of massive bit-stuffing, and system-reserved frame time for control/interrupt traffic, only 10 bulk packets are coservatively scheduled by host software. Accouniing for application-level overhead, the result is usually in 35-37MB/s range. USB drives with dual/quad memory architecture perform better.
    – Ale..chenski
    Commented Nov 11, 2016 at 0:17
  • If i add an internal PCI usb hub, and I connect an other external hub on that PCI usb card + 1 usb from the motherboard, would I get better performace?
    – rturcotte
    Commented Dec 5, 2016 at 16:11
  • If you mean another "internal PCI USB host controller card", then yes, you should be getting better performance, since each controller will operate individually, well, within your system OS driver parallelizm. I don't know how well Windows handles many concurrent bulk transfers, this use model is unlikely being well tested on personal computers. Again, you have more than 10X discrepancy between expected and achieved performance, you need to find the cause of this, the bottleneck. Start with benchmarking of your flash drives.
    – Ale..chenski
    Commented Dec 5, 2016 at 17:43

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