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  • 1.  PCIe Passthrough - to more than 1 VM?

    Posted Jul 10, 2020 09:07 PM

    Hi:

    I've not had much experience with "passthrough", but recently I needed to emergency P2V a physical server that had a SAS tape drive connection. I installed the LSI model SAS9212-4i4 SAS adapter in our R730 host server, and "passed through" the PCI device to my rehomed VM. All surprisedly works.

    Now a question has been asked, can the same PCI device be passed through to another VM?  What I read, particularly regard GPU passthroughs, seems to suggest yes, the passthrough of a device can be configured on multiple VM's.

    Am I going down the wrong road here?



  • 2.  RE: PCIe Passthrough - to more than 1 VM?

    Posted Jul 10, 2020 09:30 PM

    Only things that support

    Single Root I/O Virtualization (SR-IOV)



  • 3.  RE: PCIe Passthrough - to more than 1 VM?

    Posted Jul 10, 2020 10:00 PM

    Aeh...... SR-IOV is a little bit different.

    No, you cant share your SAS HBA to multiple VMs.

    Yes, you can assign Nvidia GPUs from a single board to different VMs when they have 2,4 onboard like the K2 and K1 Grid cards.

    Regards,
    Joerg



  • 4.  RE: PCIe Passthrough - to more than 1 VM?
    Best Answer

    Posted Jul 10, 2020 10:34 PM

    Other than Nvidia the only way is sr iov I'm aware of. that's actually how amd does it with their gpus. I was answering the over all question since that best handled every use case, in any case pci passthrough isn't a good use case in most production unless its architected for that specific use. Here is some docs that might help the original question.

    DirectPath I/O vs SR-IOV

    "With DirectPath I/O you can map only one physical function to one virtual machine. SR-IOV lets you share a single physical device, allowing multiple virtual machines to connect directly to the physical function."

    Its mainly network cards and AMD cards that use this,

    https://docs.vmware.com/en/VMware-Horizon-7/7.0/com.vmware.horizon-view.desktops.doc/GUID-131D0958-51BD-4D1F-8EB1-78BE7D4EEDA3.html

    =



  • 5.  RE: PCIe Passthrough - to more than 1 VM?

    Posted Jul 11, 2020 12:05 AM

    Thanks folks for the quick answers, all were correct in that I  can't directpath the SAS controller to multiple VM's. Sorry that I can't select more than 1 correct answer.