# Scale a Cluster

A cluster can be scaled up or down horizontally and vertically.

## Horizontal Scaling

Scaling a cluster up or down horizontally means increasing or decreasing the number of nodes available. The number of child aggregator and leaf nodes can be adjusted independently.

To adjust the number (count) of aggregators, edit the `spec.aggregatorSpec.count` field in the `sdb-cluster.yaml` file.

The value of this field is the sum of the number of Master Aggregators and child aggregators. There is only one Master Aggregator, so the number of child aggregators is always `spec.aggregatorSpec.count - 1`. Only the Master Aggregator will be deployed when this field is set to `1`.

To adjust the number of leaf nodes, edit the `spec.leafSpec.count` field in the `sdb-cluster.yaml` file. This value will be the number of leaf nodes in one availability group (AG).

## Vertical Scaling

Scaling a cluster up or down vertically means increasing or decreasing the resource capacity in each node. The following resources can be scaled up or down.

## CPU

The CPU can be scaled up or scaled down. Set the CPU request and CPU limit directly using the following fields in the `sdb-cluster.yaml` file:

* `cores`: The number of vCPUs requested for each pod.
* `coresLimit`: The maximum number of vCPUs each pod can use.

For example, to allocate 8 vCPUs to each aggregator, add the following in the `sdb-cluster.yaml` file:

```yaml
aggregatorSpec:
    cores: 8
    coresLimit: 8

```

The `cores` and `coresLimit` values are passed to the pod template as the CPU resource request and CPU resource limit, respectively. Refer to [Assign CPU Resources to Containers and Pods](https://kubernetes.io/docs/tasks/configure-pod-container/assign-cpu-resource/) for more information on Kubernetes CPU resource allocation.

## Memory

Memory can be scaled up or down. Set the memory request and memory limit directly using the following fields in the `sdb-cluster.yaml` file:

* `memoryMB`:  Specifies the amount of memory requested for each pod, in megabytes.
* `memoryLimitMB`:  Specifies the maximum amount of memory each pod can use, in megabytes.

For example, to allocate 64GB of memory to each aggregator:

```yaml
aggregatorSpec:
    memoryMB: 65536
    memoryLimitMB: 65536
```

The `memoryMB` and `memoryLimitMB` values are passed to the pod template as the memory resource request and memory resource limit, respectively. Refer to [Assign Memory Resources to Containers and Pods](https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/) for more information on Kubernetes memory resource allocation.

> **📝 Note**: The `height` parameter is deprecated. Use `cores`, `coresLimit`, `memoryMB`, and `memoryLimitMB` for explicit control over resource allocation.

## Storage

Storage can only be scaled up, and scaling up is only possible if the defined StorageClass has `allowVolumeExpansion` set to `true`.

The following fields in `sdb-cluster.yaml` control the persisted volume size for each pod, which must be expressed as integer values:

* `spec.aggregatorSpec.storageGB`
* `spec.leafSpec.storageGB`

1. To scale up storage, ensure that there is available storage space and increase these values to the desired amount.

2. Apply the new values.
   ```shell
   kubectl apply -f sdb-cluster.yaml

   ```

***

Modified at: June 3, 2026

Source: [/db/v9.1/reference/singlestore-operator-reference/scale-a-cluster/](https://docs.singlestore.com/db/v9.1/reference/singlestore-operator-reference/scale-a-cluster/)

(An index of the documentation is available at /llms.txt)