In theory, the max usb 2.0 bulk transfer speed is 52MB/sec[1], also for usb mass storage device, there are CBW(31byte), CSW(13byte) and some control info in DATA packet, so the actual usb mass storage performance is smaller than 52MB.
Generally usb device can not respond quickly enough to keep pace with usb host controller, which may degrade transfer performance much. I have seen many cheap usb disks with only less than 10MB writing performance. Also I seldom saw the usb mass storage device with above 40MB/sec transfer performance. So it is difficult to say it is a software problem or hardware problem, but if you are interested in the problem, you may use usbmon[2] to trace the transfer procedures so that we can see where the bad performance problem is. [1], 5.8.4 Bulk Transfer Bus Access Constraints of usb 2.0 spec [2], http://www.mjmwired.net/kernel/Documentation/usb/usbmon.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/932033 Title: copying files to USB 2.0 drive is damn slow To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/932033/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
