VirtualBox 6.1.30 not playing well with Hyper-V on Windows Server 2019

[mcartoixa]

I have succesfully set up a VM on my computer: VirtualBox 6.1.30 + Hyper-V on an up to date Windows 10. As it takes a lot of resources though I wanted to offload it to one of my 2 Windows 2019 Servers (and use VRDP).
But though I could install VirtualBox on both servers (with Hyper-V already activated), the VirtualBox GUI shows only minimal virtualization available, and I can only create 32bits Windows VMs.
Any idea?

[scottgus1]

If you can disable Hyper-V, or at least disable Windows' "Memory Integrity", then Virtualbox can run. Or perhaps rolling back to 6.1.26.

[mcartoixa]

Thanks for your answer. I have too much going on on these machines to turn off Hyper-V, and the fact that it works fine on Windows 10 makes me think it could be worked on Windows Server as well...
Memory Integrity is turned off on all devices (Windows 10 and Windows Server).
Version 6.1.26 has the same symptoms.

[scottgus1]

It looks like that your particular server is not one of the kinds that can run Virtualbox under Hyper-V.

I have too much going on on these machines to turn off Hyper-V

Does this mean you can't reboot? Or you have Hyper-V-based services you can't run without? You might consider running your VM under Hyper-V.

[mcartoixa]

It looks like that your particular server is not one of the kinds that can run Virtualbox under Hyper-V.

Maybe they are (I have 2 of them). But I would be very satisfied to understand what those kinds are. Can you point to any explanation?

Or you have Hyper-V-based services you can't run without? You might consider running your VM under Hyper-V.

Let's say that I am very satisfied with Hyper-V, around which I built my entire infrastructure, and I am not ready to quit. But I have this one need where I thought I could take advantage of the compatibility of VirtualBox and Hyper-V to try and host more exotic Operating Systems...

Happy New Year

[scottgus1]

Can you point to any explanation?

Not really. All we know is that some folks could run Virtualbox and Hyper-V together, some couldn't. I never knew anything about the nuts and bolts of the problem myself, I only used what the forum gurus have put together:
I have a 64bit host, but can't install 64bit guests posts 2 and 3.

the compatibility of VirtualBox and Hyper-V

That's been a long-fought slog to get to where it has gotten, and it's not all there yet. Especially when Microsoft keeps moving the goalposts. Each new version of 10/11 has a change that has to be developed for.

You could try posting a zipped log from an attempt to run a Virtualbox VM and one of the forum gurus might try to look into it.

BTW, only being able to run 32-bit 1-processor VMs means VT-x/AMD-V is being used by Hyper-V exclusively, because Hyper-V is a type-1 hypervisor, and it takes control before type-2 Virtualbox can get settled. See the 64-bits tutorial above.