3 Replies Latest reply: Feb 25, 2014 6:46 AM by Michael Black
moosehooey Level 1 (0 points)

I have a MacBook Pro with USB 3.0.  If I plug a Western Digital My Book drive into it, it's crawlingly slow (100kbps).  If I plug a USB 2.0 drive into it, it's as fast as the disk.  If I plug the USB 3.0 drive into my older Mac Mini (USB 2.0) it's also as fast as the drive.  Why is USB 3.0 so much slower than 2.0?

MacBook Pro with Retina display, OS X Mavericks (10.9)
  • Dibenkorn Level 2 (405 points)

    Are you using any of the software that came with the WD drive?  It is often incompatible with Mavericks and with OS X in general.

  • moosehooey Level 1 (0 points)

    No, it is formatted as Mac OX Extended (Journeled) and I am using it as a regular USB drive.  I am going to try updating the firmware on the drive.  I suppose I could also re-install OSX but it's a brand-new computer.

  • Michael Black Level 7 (20,382 points)

    Keep in mind that the very first device you connect will determine the default speed for the entire USB bus.  So, if you boot up the MBP, log in, and plug in a USB2 device, then the bus will never operate faster than USB2.  You would then need to reboot the computer, and first connect the USB3 device to ensure the bus steps up to USB3 speeds for USB3 devices.


    Also, make sure you are using a USB3 compatible cable with any USB3 devices to get max. transfer speeds.


    see http://support.apple.com/kb/HT5172