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  • 1.  QFX USB Speed

    Posted 07-02-2019 17:50

    Does anyone know if the QFX-5100 USB port supports 3.0 speeds? The question comes from a desire to boot from image recovery media as quickly as possible.

  • 2.  RE: QFX USB Speed

    Posted 07-02-2019 18:25

    Hi smicker,


    Yes the USB 3.0 should work as QFX5100 supports 2.0 and later:



    Have the USB FAT-32 formatted, that should work.


    Also, if trying recovery, then from the “Select a recovery image”/GNU, if we select the GRUB and follow the Junos recovery procedure with format Junos data disk and format Junos config disk, that should work.


    Hope this helps.



    If this solves your problem, please mark this post as "Accepted Solution."
    Kudos are always appreciated :).

  • 3.  RE: QFX USB Speed

    Posted 07-02-2019 21:04

    My question is if it supports 3.0 speeds. Supporting 2.0 devices or later is true of all USB 2.0 ports as well.

  • 4.  RE: QFX USB Speed
    Best Answer

    Posted 07-03-2019 15:01

    To answer my own question, and in case this information is useful to anyone else:


    The USB ports appear to be 2.0:


    usb1: EHCI version 1.0
    usb1: <EHCI (generic) USB 2.0 controller> on ehci0
    usb1: USB revision 2.0


    Data transfer speeds to a 3.0 device overall showed higher throughput than to a 2.0 device, but not dramatically so. Regardless, total time to restore from a USB install image was identical whether using 2.0 or 3.0: 7 minutes 40 seconds.


      USB2.0 USB3.0
    fs copy from 125.9Mb/s 139.9Mb/s
    fs copy from (to /dev/null) 128.5Mb/s 170.2Mb/s
    fs copy to 32.8Mb/s 52.5Mb/s
    dd copy to 35.0Mb/s 112.4Mb/s
    boot & install from USB 13.7Mb/s 13.7Mb/s