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I'm encountering a weird problem which is present both on Ubuntu 9.10 and 10.04, on two different machines.

When trying to copy between two external drives connected to the same USB controller, the transfer will randomly hang at some random time (after copying 300MB, 1GB, 10GB - it doesn't appear to depend on the dataset being copied). The hang appears to happen faster in 10.04. It appears to happen slower if both drives are connected to a hub. If the drives are connected to 2 distinct physical ports on the machine, the hang will be very fast.

Hangs cannot be reproduced if:

  1. Data is copied from the first external drive to an internal drive, then to the second external drive
  2. Drives are connected to different USB controllers, for example the first one is connected to the built-in controller and the second one via an external PCMCIA controller.

lspci says the first machine has an Intel ICH9 USB controller, the second an Intel ICH4.

Is this a hardware problem, a kernel problem or a software issue? I used Nautilus when copying the files.

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Could it be the drives are not getting enough power? Or at least one of them isn't getting enough. – Not Kyle stop stalking me Jan 18 '11 at 14:09

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