USB3 passthrough to vm with 10G

[skraw]

Hello all,

I try to passthrough some USB ports from host to linux vm and found that they all come out with 5000M speed and not 10G, although they show 10G when used on the host.
Is there a way to change this behaviour? Has anybody seen 10G USB devices inside a vm?
Thank you for comments.

 

[Nemesiz]

I'm curious, have you tried speed test?

 

[skraw]

No, have not so far. But that would not be very useful anyway as there are only HDs connected, and they lack the necessary bandwidth for the test. But I do think that passthrough USB ports should come out on the vm exactly as they were on the host, else it is no real passthrough.

 

[leesteken]

But I do think that passthrough USB ports should come out on the vm exactly as they were on the host, else it is no real passthrough.

I don't want to start a semantic discussion, but USB passthrough is not suited for high bandwidth or low latency devices and might not be considered "real passthrough" anyway. Either PCI(e) passthrough the whole USB controller or accept that it is not perfect. There are alternatives like USB/IP, with are also not perfect. VirtIO network devices and disk passthrough are in a way more similar to USB passthrough, it's not exactly emulated but also definitely not real hardware. I don't know what gave you the impression that USB passthrough is like real hardware.
Please just test if the performance is good enough and otherwise research PCIe passthrough with all its caveats and trial and error and limitations.

 

[skraw]

Hm, unfortunately the USB passthrough was not my first choice for solving the setup in question. It is only a currently working one. In fact I would have liked to passthrough the HDs as virtiofs. But since this cannot be easily exported via nfs, and nobody could tell me so far how to make a linux nfs4 server use only volatile filehandles, I am stuck to the second best - fiddling around with USB.

 

[leesteken]

Hm, unfortunately the USB passthrough was not my first choice for solving the setup in question. It is only a currently working one. In fact I would have liked to passthrough the HDs as virtiofs. But since this cannot be easily exported via nfs, and nobody could tell me so far how to make a linux nfs4 server use only volatile filehandles, I am stuck to the second best - fiddling around with USB.

I would not have guessed. If the VM is the only user of the drive, maybe disk passthrough is a option? Or PCIe passthrough of the whole USB controller? Or 9p passthrough of the drive mounted on the host. Or use a container (but load the modules on the Prioxmox host) to provide NFS? I don't know about volatile filehandles or NFS4 details, sorry. There are probably multiple ()but not simple) solution but I don't know which to suggest at the moment.

 

[skraw]

Thank you for thinking about the problem. unfortunately 9p is no solution either because it has the same problem with export via nfs than the thought-to-be-replacement virtiofs. In the longrun I will probably end up with reformatting the HDs and using ZFS instead. But at this point I simply have to preserve the HD content and am more or less stuck with USB. This is no lifesaver question for now, as it works as it is. Only I was a bit astonished about the USB inside the vm. If I remember that correctly the situation looks different on a vmware.