# Criticality

> Basic, Stable or Critical. What each criticality installs at a minimum, and which one to choose.

Source: https://docs.fransys.cloud/en/clusters/criticite/ Checked against the console on 2026-10-23.

## What criticality is for

It sets the minimum Fransys installs to keep the cluster up: control nodes, load balancer, worker machines. Above that minimum, AutoPilot or your own choices add machines within your budget.

## The three criticalities

| Criticality | What for | At least |
|---|---|---|
| **Basic** | Development, proofs of concept, demos. An occasional outage is no big deal. | A single machine is possible |
| **Stable** | Staging, internal tools, small production. | 1 control node, 1 load balancer, 1 worker machine |
| **Critical** | Production: maximum availability, even if it costs more. | 3 control nodes, 1 load balancer, 3 worker machines |

Each criticality card shows its starting price, per month.

## Basic: one machine or several

- **A single machine**: everything runs on it, with no separate control node and no load balancer. No AutoPilot. The cheapest, for testing.
- **Several machines**: Fransys adds a control node and a load balancer to keep everything up. AutoPilot becomes possible, on the Stable base.

## The recommended machine

For each criticality, the console suggests a machine:
- **Basic**: the cheapest, enough for testing;
- **Stable**: one step up, for a staging environment close to production;
- **Critical**: dedicated CPUs, for production.

You can choose another one; **Use the recommended machine** goes back to the suggestion.

## The hosting provider's requirements

Some hosting providers require a minimum number of machines for a configuration. The console shows it, for example “Hetzner requires at least 2 machines for this configuration”.

## Change the criticality

In the cluster's **Change the configuration**. Changing the criticality can add or remove control nodes: the price breakdown takes this into account before you confirm.