write/read speed between an usb 3.0 flashdisk and an usb 2.0 pc host?

[b66pak]

can anybody test the write/read speed between an usb 3.0 flashdisk and an usb 2.0 pc host?
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[sneaker_ger]

I get some 35 MB/s for both between a USB 3 HDD and a 2.0 host.

[burfadel]

As long as the USB 3.0 drive is a proper fast one, you should max out the USB 2.0 connection. USB 2.0 has a claimed 480 MBPS transfer rate, but in reality 35mb is all you will get out of it. Actually 35MB is very good! So you may ask, 8 bits per byte, so 35x8 is only 280MBPS! This is because USB 2.0 is only uni-directional. This pretty much makes it a design flaw as all transfers need to be done in both directions, even if just seemingly making the transfers go in one. The signal in the other direction is (in the most basic way of saying it), saying the transfer is going along nicely and to continue sending data. Since its uni-directional, the transfer has to pause, switch between send/receive, have the command sent/received, and switch back. This causes delays which in the case of transferring files, is around 200MBPS lost.

USB 3.0 on the other hand is bi-directional, which greatly improves transfer rate. Its important though that you use a USB 3.0 port, a USB 3.0 device, and if using a cable or external hub, that they too are USB 3.0. Having any USB 2.0 device/cable etc connected to the same internal hub (which may be connected to another USB port), will reduce the speed of all devices to USB 2.0 and switch to unidirectional mode.

[b66pak]

thanks a lot...someone with a flashdisk?
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[Chetwood]

No matter what hardware, I never got more than 32 MB which is a bad joke considering it's pitted by Intel against Firewire.