Nesting ESXi, also known as running ESXi as a virtual machine (VM) within another ESXi host, allows you to create a nested virtualization environment. This setup is commonly used for testing, learning, and development purposes. It enables you to experiment with features and configurations without the need for physical hardware. Below is a detailed process to deploy nested ESXi hosts:

Prerequisites:

1. A physical ESXi host or a hypervisor that supports hardware virtualization (e.g., VMware Workstation, VMware Fusion, or VirtualBox).
2. VMware vSphere/ESXi installation ISO for the version you want to deploy as nested ESXi.

Step 1: Prepare the Physical Host or Hypervisor: Ensure that the physical host or hypervisor has hardware virtualization (Intel VT-x/AMD-V) enabled in the BIOS settings. Verify that you have enough CPU, memory, and storage resources to run multiple nested ESXi VMs.

Step 2: Create a Virtual Machine for Nested ESXi:

1. Open your virtualization software (e.g., VMware Workstation) and create a new virtual machine.
2. Choose “Custom” or “Typical” configuration and select “I will install the operating system later.”
3. Choose the guest operating system as “Other” and select the appropriate version (e.g., “Other 64-bit” if deploying ESXi 64-bit).
4. Configure the VM’s CPU, memory, and storage settings based on your requirements. Ensure that you allocate sufficient resources for the nested ESXi VM to function properly.

Step 3: Add a Virtual Network Adapter:

1. In the VM settings, add a virtual network adapter to the VM.
2. Connect the virtual network adapter to a virtual network that provides network connectivity to the nested ESXi VM.

Step 4: Install Nested ESXi:

1. Power on the nested ESXi VM.
2. Mount the ESXi installation ISO to the VM’s CD/DVD drive.
3. Follow the ESXi installation wizard to install ESXi as you would on physical hardware.
4. During the installation, select the appropriate disk and configure networking settings.

Step 5: Configure Nested ESXi Host:

1. After the installation completes, reboot the nested ESXi VM.
2. Assign an IP address to the nested ESXi host through the ESXi console or vSphere Client.

Step 6: Configure Nested ESXi Networking:

1. In the nested ESXi host, navigate to the networking settings and configure virtual switches and port groups to provide network connectivity to VMs running on the nested ESXi host.

Step 7: Enable Nested Virtualization in Nested ESXi VM:

1. SSH to the nested ESXi host (enable SSH if not already enabled).
2. Edit the ESXi configuration file /etc/vmware/config and add the line vhv.enable = "TRUE" to enable nested virtualization.
3. Save the configuration file and reboot the nested ESXi VM.

Step 8: Test Nested ESXi:

1. Once the nested ESXi host is up and running, you can use the vSphere Client or vSphere Web Client to connect to the nested ESXi host.
2. Create and manage VMs on the nested ESXi host, just like you would on a physical ESXi host.

Important Note:

1. Nested virtualization is primarily intended for testing and learning purposes. It may not be suitable for production workloads due to performance limitations.
2. Nested ESXi VMs require sufficient resources, including CPU, memory, and storage, as they run multiple virtualization layers.
3. Nested ESXi hosts should not be added to production vCenter environments as this is an unsupported configuration.

Always ensure that you have adequate hardware resources and review VMware’s official documentation and compatibility guides for nested virtualization before deploying nested ESXi hosts.