Oxide's Voxel Emulates a Full Rack-Scale Server on a Single Mini-PC

Oxide Computer Company has released Virtual Oxide Labs, or Voxel, a software emulator that models an entire Oxide rack — compute sleds, network switches, and the microcontrollers that manage the hardware — on a single machine. According to the company's blog post, an engineer can boot a complete virtual rack with six sleds in roughly ten minutes on a mini-PC with 96GB of RAM, no physical rack required.

The problem it solves

Oxide builds and sells whole racks, which creates an awkward testing problem: finished hardware ships straight to customer data centers, leaving little spare capacity for development and quality assurance. The company's Product Assurance team says it needs to replicate diverse customer network topologies, run the real control plane, test up-to-date builds, and represent hardware components such as switches and microcontrollers — all without cutting special test-only releases.

Oxide already had partial answers. It operates four compact "racklettes" — genuinely real racks, just in a non-saleable form factor of four sleds and two switches each — with four more on the way. Parts of the Omicron control plane can also run in various degrees of simulation. Voxel, the successor to an earlier virtual lab effort called a4x2, goes further by combining everything into one emulation stack.

How the emulation works

A principle Oxide attributes to Bryan Cantrill — the "Prime Directive" — is that labs must run stock Oxide software without hack or modification. Voxel is built on illumos in Rust and leans on several of the company's existing components:

• Propolis, Oxide's hypervisor technology, hosts each virtual sled in its own VM; switches run in Propolis VMs as well.
• Networking uses BGP, numbered or unnumbered, or static routing, handled by Debian VMs running FRR.
• Switches are emulated through SoftNPU, Oxide's software P4 switch.
• The Service Processor and Root of Trust microcontrollers — an STM32H753 and an LPC55 — are emulated and flashed with the real Hubris firmware.

Images are built as reusable ZFS snapshots. Voxel installs the Omicron control plane into a virtual machine, either by compiling it from source with cargo or by unpacking an official release packaged with The Update Framework, then captures the disk before configuration happens. Launching a rack then needs only that control plane image, an FRR image for the network VMs, and voxel-init, a lightweight Rust agent that hands each virtual sled its assignment.

During launch, an automated network topology suite called falcon wires the network with simnet and VNIC pairs, trust material is generated as sprockets PKI, and the emulated microcontrollers are flashed. In one documented example, six Propolis VMs started — three acting as Oxide sleds and three driving the network — after which voxel-init configured NAT and uplink addressing, underlay networking, emulated M.2 boot disks and five U.2 data disks, seeded host images, activated the per-sled agent, and drove the rack through its initialization phases via wicketd. Multirack setups, two racks sharing one management plane, are also supported; the author notes that adding a new interconnect between virtual racks is a few lines of code in rack.rs.

The hardware bar is low

The post's author reports running Voxel at home on a Minisforum MS-A2 mini-PC with a 32-thread AMD Ryzen 9 9955HX and 96GB of RAM, hosting six sleds either as a single rack or in a multirack configuration. The software requirements are Oxide's Helios and a decently fast NVMe drive.

Current limitations

Voxel does not yet fully satisfy the Prime Directive: the certificates in the sprockets PKI are generated at launch rather than being set at manufacturing and rooted in the Root of Trust the way production racks do. According to the post, this doesn't affect actual rack runtime, so it remains an accepted gap.

Why it matters

Rack-scale systems have traditionally been tested on the very hardware customers are waiting for. By moving that work into an emulator that runs stock release artifacts on commodity machines, Oxide can test exactly what it ships, keep CI lean, and let engineers develop against rack-scale behaviour without a rack. The release, which reached the front page of Hacker News, also illustrates a broader shift in the industry: full-system emulation, down to microcontroller firmware, is now practical enough that an entire data center rack can live on a desk.