I have two Dell U2412M monitors, both of which have USB hubs built into them. I have one of those hubs connected to my MacBook Pro directly, and that hub has a webcam plugged into it.

I want to connect my second monitor's hub to the first monitor's hub (which is connected to my laptop) and then plug in my desktop 3.5" self-powered HDD drive to that second hub.

It would look like this:

Example layout

I am already aware that this would mean I would be sharing bandwidth with all the other devices connected to the hub, but I use my external HDD purely for backup so I would never be using my webcam and HDD simultaneously.

I'm more concerned about data integrity than I am about speed. Would daisy chained monitor usb hubs be reliable enough of a connection to transfer data over to a drive?

Also, side-note: The only tool I could find to determine if these Dell monitors have bus powered or self powered hubs was Microsoft's own USBView (or even the Device Manager) so I checked it via my VM and sure enough it says they are self-powered. I suppose it makes sense but I can't find any official word about that from Dell or elsewhere.

  • 1
    Usually all devices that include an USB hub and that already have an own power supply are self-powered. – Robert Jul 14 '12 at 17:27
  • That's definitely what I would have thought, but even as evidenced by the answer below, info on that is not solid. – raffi Jul 15 '12 at 23:51

I think the USB protocol includes many error detection and recovery techniques that prevents data corruption.

Also, unlike analog amplifiers, the usb hubs are completely digital devices that will completely regenerate the singals from the the logical data, so attenuation and noise is generally not a concern here as long as your cable length is within the standard.

On top of these, many file systems have read-back checks to make sure the data written is exactly what is intended.

As to your second question, based on my exprience, the hubs on dell monitors are not powered.

  • Interesting insight on the USB protocol. Do you have any source for the error detection and recovery part? I do believe digital transfer might make data corruption less likely, but I don't really think it does any checksums upon transfer unless you do it manually. Also, by 'not powered' do you mean they are bus powered despite the monitor having it's own power source? Or do you mean that they do not charge devices when the monitor is off? My interest is in the first scenario. – raffi Jul 16 '12 at 0:05

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