How it works
A program called a hypervisor runs on the physical server. It carves the hardware into several virtual machines. Each one gets virtual processors, a fixed amount of memory, a virtual disk and a virtual network card.
The virtual disk is usually just a big file on the host. The virtual processors are slices of time on real cores. Modern processors help with this: the hardware itself separates what the guest does from what the host does, so a VM runs at close to native speed.
Inside, you install any supported operating system and treat it as a normal machine. It has its own kernel, so a crash or a reboot in one VM does not touch its neighbours. You can check from the inside that you are in one:
$ systemd-detect-virt kvm $ lscpu | grep -i hypervisor Hypervisor vendor: KVM
A machine you can save and copy
Because the whole computer is software, its state is data: memory, disk, even the position of every running program. A hypervisor can pause a VM, save that state to a file and start it again later. It can also copy the file and start a second machine from the same point.
This is what makes VMs useful for more than renting a server. You can take a snapshot before a risky upgrade, roll back after a mistake, or clone a working setup ten times. A physical server can do none of this.
VM, container or physical server
| Physical server | Virtual machine | Container | |
|---|---|---|---|
| Own kernel | Yes | Yes | No, shares the host's |
| Own root and system packages | Yes | Yes | Inside the container only |
| Can be saved and copied | No | Yes, memory and disk | Files yes, running state rarely |
| Shared with other customers | No | Yes | Yes |
| Weight | Heaviest | A full operating system | One app and its libraries |
A VPS is a virtual machine you rent with an address on the internet. The longer comparison with containers and sandboxes is in VPS, VM, container, sandbox.
Do you need one?
Take a virtual machine when
- You need your own kernel. Custom kernel modules, a firewall, a VPN, anything below the app.
- You need a machine to stay. A bot, a database or an agent that keeps state for weeks.
- You run code you do not fully trust. A VM has its own kernel, so the code does not run on the host's.
Skip it when
- You ship one app. A container starts faster and is easier to move.
- It is a static site. Static hosting needs no machine at all.
- You want a result and not a machine. A hosted service saves the upkeep.
A virtual machine in Uno
Every Uno computer is its own VM: a Firecracker microVM, one per computer, root inside. You get Docker and your own disk. With nothing to do for 10 minutes it sleeps. Memory and running programs are saved, and the first request wakes it. How the computer works.
Small: $5 a month
Pick the size of your virtual machine
Every plan is a real Linux machine with root and Docker. Move up or down in the console and your files come with you.
Small
A Telegram bot, a VPN, a small backend
$5/ month
- 1 vCPU · 1 GB
- 15 GB disk
- 25 GB cloud storage
- 5 boosts a month
Plus
Agents that work with your laptop closed
$20/ month
- 4 vCPU · 4 GB
- 40 GB disk
- 100 GB cloud storage
- Uno Work in the cloud
Pro
A product in production, a second MacBook
$70/ month
- 16 vCPU · 16 GB
- 120 GB disk
- 300 GB cloud storage
- Speed of a MacBook Air M4
Max
A team and many agents at once
$200/ month
- 32 vCPU · 48 GB
- 300 GB disk
- 1,024 GB cloud storage
- 5 public IPv4
Add Uno AI to any plan: 40 h of AI work a month on Small, 100 h on Plus, unlimited on Max. Today: GLM-5.3 Flash and MiMo v2.6 Pro. Or sign in with your own Claude or ChatGPT.