On Tue, 23 May 2006, Norbert Preining wrote: > Hi all! > > I own an iriver H300, ie an external hard disk. When I connect it via > usb2 to my laptop or desktop pc I often get > usb 2-2: reset high speed USB device using ehci_hcd and address 2 > This happens often, although it does not ruin the files nor creates > other problems (besides the time until the device is resetted and the > copying continues).Just now I coied 5.4Gb to the device and it was > resetted around 25 times.
> So my question is: Is this behaviour to be expected, or should this be > tracked? And if yes, how? It's not expected but it's also not uncommon. Although 25 times in 5.4 GB (how many minutes was that?) sounds like a lot. USB, like other data buses, occasionally encounters data transfer errors. High-speed transfers are particularly vulnerable because the electronic tolerances need to be so much tighter than for slower speeds. When an error occurs, usb-storage resets the device. If the reset works properly, no data is lost -- only a little time. As you saw. You might ask how the error rate can be reduced. It depends on the cause (obviously), which usually is hard to determine. It could be low-quality USB cables, bad impedances at the connectors, electromagnetic interference, timing variance near the tolerance limit, firmware bugs, or something else. Often you can fix the problem by replacing one or more of: your USB host controller, your USB cable, your USB device (or the device's USB interface). For example, I've got a USB disk-drive/cable/host-controller combination where the three together do not work at all, but replacing any one of the three fixes the problem. Try and figure that out! Alan Stern ------------------------------------------------------- All the advantages of Linux Managed Hosting--Without the Cost and Risk! Fully trained technicians. The highest number of Red Hat certifications in the hosting industry. Fanatical Support. Click to learn more http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
