The Californer - eRacks Names Its Default Hypervisor: KVM on Ubuntu, Installed Since 2007, With eVirt Now Offered

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The open-source server maker explained why plain Ubuntu plus KVM is the host it recommends, why Proxmox and IncusOS run on the same kernel module, and offered its in-house eVirt framework on a consulting basis.

CAMPBELL, Calif. - Californer -- eRacks Open Source Systems today published its position on server virtualization: the hypervisor it has recommended, installed and run on its own machines since 2007 is KVM, the Kernel-based Virtual Machine, on Ubuntu Server. The post follows the company's notes on IncusOS, the new immutable operating system built around Incus, which compared Proxmox, XCP-ng and ESXi and left out the option eRacks uses most often.

A hypervisor is the layer that lets one physical machine run several virtual machines. KVM is not a separate product: it entered the Linux kernel in version 2.6.20 in February 2007 and has shipped in every mainline kernel since. Proxmox VE and Incus, the runtime IncusOS exists to run, both run their virtual machines on KVM and QEMU, so choosing between them is choosing a management layer, not a hypervisor.

eRacks also described eVirt, the small framework its own production web, mail and lab servers have run on since 2007, now in its fourth version. Each machine is a short YAML file: CPU, memory, disks, bridge and a fixed address. One command fetches an Ubuntu cloud image, seeds it with cloud-init and starts it under KVM through QEMU's monitor. eVirt is not packaged as a product; the company installs it for customers on a consulting basis. Wolff attended the first KVM Forums, in Tucson in 2007 and Napa in 2008, learned the design from Avi Kivity and the kernel developers who wrote it, and began eVirt as a libvirt alternative soon after; that story is the subject of a follow-up post.

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"Most of what leaves our bench runs virtual machines, and the hypervisor is usually the kernel that is already there," said Joseph Wolff, founder and CTO of eRacks Systems. "Proxmox, Incus and plain Ubuntu are three ways to manage the same KVM. We build the hardware and storage under all of them and install whichever one the customer asks for."

Virtualization hosts ordered without a named platform ship with Ubuntu Server LTS, QEMU and KVM installed and tested, plus the management layer of the customer's choice.

The full post is on the eRacks blog: https://blog.eracks.com/2026/09/kvm-on-ubuntu-since-2007/