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How to Enable Nested Virtualization On Proxmox?

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enable nested virtualization

If you have a proxmox server with very large resources but we want, for example, to make a failover simulation on proxmox which should use at least 2 servers, then we can activate nested virtualization on proxmox.



How to enable nested Virtualization on proxmox?



In short, nested virtualization is running a VM within a VM. In this case, I would enable nested virtualization on proxmox 7.2 to install CentOS on Proxmox VM. Open the proxmox CLI as root user and if your server uses an intel processor, then write the command below:

cat /sys/module/kvm_intel/parameters/nested


but if you are using an AMD processor then type the command below:

cat /sys/module/kvm_amd/parameters/nested


If the result of the above command produces a Y output, it means that it enabled the nested virtualization function. But if the output is N, it means that the function is still disabled. To enable, then type the command below:

For Intel:

echo 'options kvm-intel nested=Y' > /etc/modprobe.d/kvm-intel.conf


For AMD:

echo 'options kvm-amd nested=1' > /etc/modprobe.d/kvm-amd.conf


After that use the command below to reload the kernel module:

For Intel:

modprobe -r kvm_intel
modprobe kvm_intel


For AMD:

modprobe -r kvm_amd
modprobe kvm_amd


After that do the command again to check nested virtualization using the command below:

For Intel:

cat /sys/module/kvm_intel/parameters/nested


For AMD:

cat /sys/module/kvm_amd/parameters/nested


and the nested virtualization function should be active, as shown below:

Checking nested virtualization

After that, create a VM (I install Proxmox) and on the CPU tab, select the host on Type column as shown below:

Change in the Host tab

Before installing the VM, check the Hardware section for the VM, it will look like the image below:

Display Processors tab

Then change the KVM hardware virtualization in the Options section to Yes, as shown below:

Change the KVM hardware virtualization

After that do the installation of Proxmox and if it is finished, then try to install any OS (I install CentOS) on proxmox that we have installed previously and the OS should be able to run normally.



If you install Proxmox on the Proxmox server and you get an error like the below image:

Error when installing Proxmox

No support for KVM virtualization detected.
Check BIOS settings for Intel VT / AMD-V / SVM.

It means the VM detected there is no KVM Virtualization on the server or on the Proxmox Application. If you are sure your server has been configured to enable nested virtualization, you must check the configuration of Proxmox, especially in the section selecting the host as the CPU type and changing to Yes in the KVM hardware virtualization section.



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