Building a VMware Sandbox with Nested ESXi Inside Proxmox

A home lab is the cheapest way to learn vSphere features before risking them in production. By running a nested ESXi install on top of Proxmox, you can spin up a full VMware cluster on one physical box, complete with vCenter, HA simulations, and NSX-lite networking, without paying for licensing beyond the ESXi evaluation period.

Proxmox VE is well suited as the outer hypervisor for this kind of setup. It's KVM-based, free, and supports nested hardware-assisted virtualisation out of the box. The combination gives Australian IT practitioners a low-cost way to keep practising VMware skills while head office in distant time zones reviews the Sydney and Brisbane data centre contracts.

Before you start burning weekend hours, it pays to think about power. Electricity in Perth and Adelaide is among the most expensive in the country, so picking efficient hardware is more than an environmental choice, it is a monthly bill conversation that compounds quickly.

What follows is a practical walkthrough: the hardware you need, the BIOS tweaks that matter, how to provision the inner ESXi VM, and how to keep the lab tidy with snapshots once you are done experimenting.

Verifying Your Hardware Supports Nested Virtualisation

The CPU has to expose hardware virtualisation extensions and the nested feature. On Intel chips, look for vmx and the "nested" flag in /proc/cpuinfo. On AMD, the equivalent is svm. Practically, anything from a Xeon E3 v5 onwards or a Ryzen 5 3600 and up will do the job comfortably for most lab tasks.

Memory is the next bottleneck you will hit. The outer Proxmox host, plus one nested ESXi VM with two nested workloads inside, needs at least 32 GB. If you plan to run vCenter, vSAN, or a few NSX components, push to 64 GB. NVMe storage helps with sync storms during heavy lab exercises, so a single 1 TB Samsung 980 or WD SN770 is usually plenty.

Networking wise, a single gigabit port is fine for the host, but if you want distributed switch exercises, plumb a second physical NIC through and present it to the nested VM as a passthrough device.

Preparing the Outer Proxmox Host

Download the latest Proxmox VE ISO from the upstream project and flash it via Balena Etcher or similar. During install, accept the defaults but pay attention to filesystem choices; ZFS on a single disk is fine for a lab and gives you snapshots you will thank yourself for later.

Reboot and open the management UI at https://your-ip:8006. Before creating anything, enable nested virtualisation on the host with the following commands:

echo "options kvm_intel nested=1" > /etc/modprobe.d/nested.conf update-initramfs -u && reboot

The equivalent command for AMD hosts uses kvm_amd. Once the system comes back up, cat /sys/module/kvm_intel/parameters/nested should return Y, confirming nested guests can run.

Provisioning the Nested ESXi Virtual Machine

In Proxmox, click Create VM and choose the ISO you downloaded from VMware's Customer Connect portal; the free evaluation is enough for any home lab. The machine type must be q35, and the CPU should be set to host type so the nested feature flags are exposed to ESXi.

Allocate at least 8 GB of RAM and four cores. ESXi will refuse to install if it cannot detect at least 4 GB, and you will thank yourself for the headroom once you add a couple of nested workloads. For the disk, many lab builders stick with the LSI 9 (virtio-scsi-single) or SATA controller for compatibility, even though VirtIO SCSI is faster. A 200 GB thinly provisioned disk is plenty.

Before booting, expose hardware-assisted virtualisation to the guest. In the VM's Processor tab, set Type to host and tick the boxes for AMD-V or Intel VT-x. Without this flag, ESXi installs but cannot itself run nested guests, which defeats the purpose of the exercise.

Installing ESXi Inside the VM

Boot the VM and let the familiar ESXi installer take over. You will see the usual prompts for keyboard layout, root password, and disk selection. Where ESXi warns about limited support for the virtual NIC, accept it; the nested host will work fine over the VM's virtual network interface created on the Proxmox side.

When the installer finishes, you will see the classic DCUI screen with the management IP address. If DHCP is available on your Proxmox bridge, the address appears automatically. Otherwise, press F2, log in, and configure a static IP that fits your home range. Many Australian labs sit on 192.168.0.0/16 or 10.0.0.0/24 ranges inherited from off-the-shelf routers shipped through JB Hi-Fi or bundled by Telstra.

Reboot the inner VM, then connect from your laptop via the host client or browser at https://nested-esxi-ip/ui. Confirm that the network is reachable and that you can apply licensing changes from the menu before moving on.

Linking Your Lab to the Wider Virtxpert Series

Once the bare nested host is up, the natural next step is vCenter. A tiny VCSA appliance can itself run inside the same Proxmox host if you give it 12 GB and four cores, and it serves as the management plane for the rest of the cluster.

This is where a structured walkthrough pays off. Jonathan Frappier's VMware walkthrough series covers vCenter, vSAN, NSX, and the rest of the stack in the order most home-lab builders actually consume them, and it pairs well with the setup described here. Working through the early pieces in order will give you a working nested cluster before you reach the troubleshooting episodes further along.

Good Habits Before You Start Tinkering

After the first successful boot, set up a few safeguards so a quick experiment does not cost you a full weekend rebuild. The list below keeps the lab predictable as it grows.

• Keep Proxmox ZFS snapshots of the inner VM before each big change, so a bad vSAN config can be rolled back in seconds rather than rebuilt from scratch.
• Disable time drift inside the guest by enabling NTP synchronisation against an Australian pool such as au.pool.ntp.org, which prevents certificate errors when VCSA and the nested hosts talk to each other.
• Document MAC addresses for the VMkernel adapters so you can rebuild networking quickly after a mistake.
• Set memory ballooning off at every level of the stack; it causes instability when nested hypervisors start swapping under load.

When the long provisioning steps have you waiting, take a quick break. Resources such as fast casino games exist for exactly that sort of downtime, and they have nothing to do with the lab itself. Just remember to save your vCenter config before you close the lid.

Picking Up Free Tooling to Speed Up the Lab

A few community utilities save real time once the basic cluster is responsive. For instance, before you reach for PowerCLI installers, pull a couple of ready-made scripts from Virtxpert's free PowerCLI tools page; they handle bulk VM creation, snapshot rotation, and report generation without requiring much custom code on your side.

Pair those scripts with the host client's built-in tasks and you have a reproducible lab in an afternoon. Bookmark the free tools page now so you do not forget which scripts you ended up relying on as the lab grows into a multi-host cluster.

Build your nested ESXi on Proxmox this weekend and document every failed config as carefully as the working ones. Subscribe to Virtxpert for the next article in the series, drop your questions in the comments, and share what you build so the home-lab community in Australia and beyond keeps getting stronger with each shared note.