USB 2.0 device performance through USB 3.0 hub

Discussion in 'Mac Accessories' started by Morien, Jul 4, 2012.

  1. Morien macrumors member

    Joined:
    Oct 25, 2010
    #1
    Hi,

    How do USB 2.0 devices (specifically hdds) perform through a USB 3.0 hub? Do they go full speed (when both being accessed at the same time) with the extra Usb3 overhead? Or does it perform the same as a usb2 hub? (with both devices competing for bandwidth)?

    Also, I have noticed that some hubs have USB 3.0 specific ports, along with USB 2.0 specific ports. The hubs I have found near me for sale though just have USB 3.0. I have heard that plugging a usb2 device in along with a usb3 will slow down all devices to usb2 speeds. Is this true?

    Thanks
     
  2. Comeagain? macrumors 68020

    Comeagain?

    Joined:
    Feb 17, 2011
    Location:
    Spokane, WA
    #2
    Any device will "max out" at the slowest piece of the signal chain. Ie, a USB 2.0 external drive will be that same speed whether using USB 2 or 3, even going through Thunderbolt, it will always be USB 2 speed.
     
  3. Morien thread starter macrumors member

    Joined:
    Oct 25, 2010
    #3
    Hey comeagain,
    I know that I won't experience any increase in speed, but what I'm asking is if I would experience a slowdown comparable to if two drives were connected to a usb2 hub and accessed at the same time (for simplicity sake, we'll just assume that the bandwidth of the usb2 hub is evenly halved, causing both devices to go at half speed).

    So, since USB3 supports a speed of up to 625MB/s max, would two usb2 drives (60MB/s max theoretically) be able to transfer data simulateousoy at their max speed (a combined 120MB/s)? Or would they act as if they are both connected to a USB2 hub (a combined 60MB/s, or 30MB/s each)?

    Thanks a lot
     
  4. theSeb macrumors 604

    theSeb

    Joined:
    Aug 10, 2010
    Location:
    Poole, England
    #4
    Real world USB 2.0 performance is around 25-30 MB/s, not 60 MB/s. Whether you get half the bandwidth or not when using a hub depends entirely on the hub. With a USB 3 hub, you would get your maximum USB 2 performance for each USB 2 device that is connected. Unless you bought it for $5.
     
  5. Morien thread starter macrumors member

    Joined:
    Oct 25, 2010
    #5
    Hey theseb,

    I know that real world speeds are lower, but you've answered my question. Thanks
     

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