PCIe Passthrough - to more than 1 VM?

[CISNY]

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?

[sjesse]

Only things that support

Single Root I/O Virtualization (SR-IOV)

[IRIX201110141]

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

[sjesse]

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

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[CISNY]

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.