Running into a problem with a Server 2016 machine being used a DC and file server for our small office. Hardware is a SuperMicro SuperServer 1029P-MTR. 2 Xeon Silver 4110 8 core processors, 32GB Ram. We have Server Core installed as a hypervisor and then an instance of a full Server 2016 (64 bit) installed as a VM. It's the only running VM on the server at the moment. I had previously allocated 16GB of RAM to it, and we were having some speed issues that I started investigating.
In Resource Monitor, I discovered that of the 16GB allocated, 11GB was "Hardware Reserved", leaving only 5GB for everything else. I changed the VM settings to allow 24GB to the VM. The Resource Monitor now shows 19GB as "Hardware Reserved", leaving the same 5GB available. The VM sees the full 24GB as "Installed Memory".
(The rest of the VM memory settings are: RAM - 24000MB, Enable Dynamic memory checked, minimum RAM 512MB, maximum RAM 1048576 MB, Memory Buffer 20%, Memory Weight slider set to highest setting)
Following some hints here, I've looked at Device Manager to see what hardware had memory allocated. It looks like 8GB (!) is allocated to "Microsoft Hyper-V Video" and another 4MB assigned to each of two "Advanced programmable interrupt controller" (total of 8MB).
Not sure if 8GB is normal for Hyper-V video, but that doesn't explain the rest of the missing RAM, or why the reserved portion increased when I increased the memory allocation...
Any advice on how to resolve this and release the memory?