> ## Documentation Index
> Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Engine Scaling

> Scale up, scale down, and stop a Firebolt Engine.

## Engine Scaling

Firebolt Engine supports scaling up and down by patching the `spec.replicas` field. The Firebolt Operator
handles the transition automatically, applying one of the rollout strategies defined in [Engine Rollouts](./engine-rollouts).

## Scale or update

Patch `spec.replicas` to scale the engine:

```bash theme={"theme":{"light":"css-variables","dark":"css-variables"}}
kubectl patch fireng my-engine -n firebolt \
  --type merge -p '{"spec":{"replicas":2}}'
```

The Firebolt Operator handles the zero-downtime transition automatically.

## Stop and resume

Set `spec.replicas` to `0` to stop the engine without deleting the custom resource:

```bash theme={"theme":{"light":"css-variables","dark":"css-variables"}}
kubectl patch fireng my-engine -n firebolt \
  --type merge -p '{"spec":{"replicas":0}}'
```

Resume by setting a non-zero replica count:

```bash theme={"theme":{"light":"css-variables","dark":"css-variables"}}
kubectl patch fireng my-engine -n firebolt \
  --type merge -p '{"spec":{"replicas":2}}'
```