• This topic has 9 replies, 6 voices, and was last updated May 24, 2021 by Joseph L.

VMXNET3 DirectPath I/O Enabled

  • We have ESXi 6.5 in our environment.  We’re looking at turning off DirectPath I/O for any VMXNET3 adapters.  The VRA’s have it enabled.  Is that by design?  It is a ‘bug’ and turns on by default so we manually turn it off on our VM’s that we create.


    Contara from Zerto Support.

    The VRA is deployed with a VMXNET3 adapter, which is a 10 Gbps vNIC. A VRA cannot utilize multiple vNICs to improve throughput. This means that a single VRA is bound to 10 Gbps, or 1,250 MBps as a theoretical maximum.

    Thank you.

    Hi Contara,

    Being that the VRA is limited to one vNIC, it seems DirectPath I/O is turned on by design to provide better performance? Looking for clarification. Thanks!


    This is Kalsang from Zerto support.

    Yes, DirectPath I/O is turned on by design to provide better performance.

    Best regards,

    What if we’re utilizing Nutanix clusters with ESXi hypervisor? From what Nutanix keeps telling me. Due to the storage locality, the Direct Path I/O option is recommended to be disabled on all VMware virtual machines.

    Would we still keep it enabled for just the Zerto VRA VM’s?

    I understand the use case for Direct Path if running a tiered architecture like a Flex-Pod or something. Considering vxRail and Nutanix hyper-converged designs, is this still the case?

    Hello Joseph,


    I am Joseph with Zerto. I am investigating your inquiry and will provide a status soon.


    Thank you,


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