> ## Documentation Index
> Fetch the complete documentation index at: https://docs.streamnative.io/llms.txt
> Use this file to discover all available pages before exploring further.
# Resize a Cluster
[Serverless clusters](/cloud/clusters/cluster-types#serverless-clusters) are elastic and automatically scale based on workloads. There is no need to manually size or resize a Serverless cluster.
This topic describes how to resize an existing StreamNative cluster, including Dedicated, BYOC, and BYOC Pro clusters. These clusters are provisioned and billed in terms of [CUs and SUs](/cloud/billing/billing-overview#cu-su). Evaluating the number of CUs and SUs your cluster requires helps you reduce costs or scale to meet your data streaming needs.
When you resize a StreamNative cluster, StreamNative automatically redistributes the traffic to help ensure a balanced load across the remaining brokers in the cluster. If you're reducing the size of the cluster, StreamNative removes unused brokers at the end of load balancing and removes unused bookies after re-replication.
Once you request a resize for your cluster, you cannot request another update until the initially requested resize has completed.
## Resize a Cluster
This section shows you how to resize an existing StreamNative Cloud cluster, including scaling up and down the cluster and adjusting the required resources.
Prerequisites:
* An existing [StreamNative Cluster](/cloud/clusters/cluster-types)
You can expand the number of CUs and SUs in the StreamNative Cloud Console.
1. Log in to the [StreamNative Cloud Console](https://console.streamnative.cloud/).
2. Navigate to the [**Cluster Workspace**](/cloud/get-started/cloud-console#cluster-workspace).
3. Click **Configuration** in the left navigation pane to access **Cluster Configuration**.
4. On the **Cluster Configuration** page, click the **Edit Cluster** button in the top-right corner. You will be redirected to the **Cluster Provisioning** page where you can update the cluster configuration and adjust the sizing of the cluster.
5. Skip the **Cluster Configuration** page by clicking the **Cluster Size** button. You will be redirected to the **Cluster Size** page.
6. On the **Cluster Size** page, you can choose between **Basic** or **Advanced** mode to expand the cluster.
* **Basic Mode**: Use the slider to adjust the required throughput. StreamNative Cloud will automatically calculate the number of brokers and bookies, as well as their respective CUs and SUs per node.
* **Advanced Mode**: Manually adjust the number of brokers, bookies, CUs, and SUs per node.
7. Click the **Finish** button to complete the cluster expansion.
The cluster will start scaling up, and you will be redirected to a **Deploying** page that shows the progress of the deployment process. The deployment might take a few minutes to complete, depending on how many resources you are scaling up. You can always click **Go To The Dashboard** to return to the **Cluster Dashboard** page. You can see the number of brokers and bookies in real-time on the **Cluster Dashboard** page.
CUs and SUs are reflected as the number of CPU and Memory used by the brokers and bookies. When expanding a cluster via `snctl`, you can modify the number of bookies and brokers, as well as their corresponding CPU, Memory, and Disk resources. This is done by updating the **PulsarCluster** Custom Resource Definition (CRD).
To expand your cluster using [`snctl`](/tools/cli/snctl/snctl-overview), follow these steps:
1. Retrieve the current cluster configuration:
```
snctl get -O pulsarcluster -o yaml > cluster-config.yaml
```
2. Edit the `cluster-config.yaml` file to increase the resources. For example:
* Increase the number of brokers or bookies:
```yaml theme={null}
spec:
broker:
replicas: 5 # Increase from default 3 to 5
bookkeeper:
replicas: 4 # Increase from default 3 to 4
```
* Adjust the CPU, memory, or storage for brokers or bookies:
```yaml theme={null}
spec:
broker:
resources:
cpu: '4'
memory: '8Gi'
heapPercentage: 50
directPercentage: 50
bookkeeper:
resources:
cpu: '4'
memory: '8Gi'
heapPercentage: 50
directPercentage: 50
ledgerDisk: '100Gi'
journalDisk: '50Gi'
```
These examples demonstrate how to modify the PulsarCluster CRD to scale your cluster's resources.
3. Apply the updated configuration:
```
snctl apply -f cluster-config.yaml
```
After `snctl apply` is completed, the cluster will initiate the expansion process. The operation may take several minutes to complete, depending on the scale of the expansion.
You can check the status of your PulsarCluster to monitor the progress. The PulsarCluster resource includes a status block that provides valuable information about the current state of your cluster components.
To check the status, you can use the following command:
```bash theme={null}
snctl clusters -O get -o yaml
```
Here's an example of what the status block might look like:
```yaml theme={null}
status:
bookkeeper:
readyReplicas: 3
replicas: 3
updatedReplicas: 3
broker:
readyReplicas: 3
replicas: 3
updatedReplicas: 3
```
When all the `readyReplicas`, `replicas`, and `updatedReplicas` are the same, the cluster expansion is complete.
CUs (Compute Units) and SUs (Storage Units) are reflected in the CPU and memory resources used by brokers and bookies, respectively. When expanding a cluster via the **Terraform Provider**, you can modify the number of bookies and brokers, as well as the CUs per broker and SUs per bookie. This is accomplished by updating the [**streamnative\_pulsar\_cluster**](https://registry.terraform.io/providers/streamnative/streamnative/latest/docs/resources/pulsar_cluster) resource.
To resize a cluster using the StreamNative Terraform Provider, follow these steps:
1. Update your Terraform configuration file (e.g., `main.tf`) to modify the cluster resources. Here's an example of how to update the cluster configuration:
```hcl theme={null}
resource "streamnative_pulsar_cluster" "my_cluster" {
# ... other configuration ...
broker_replicas = 5 # Increase the number of broker replicas
bookie_replicas = 5 # Increase the number of bookkeeper replicas
compute_unit = 0.4 # Increase compute units per broker
storage_unit = 0.4 # Increase storage units per bookie
config {
# ... other configuration ...
}
}
```
```
This example demonstrates how to modify the `streamnative_pulsar_cluster` resource to scale your cluster's resources.
```
2. After updating the configuration, run the following Terraform commands:
```bash theme={null}
terraform plan
```
This command will show you the planned changes to your StreamNative cluster.
3. If the plan looks correct, apply the changes:
```bash theme={null}
terraform apply
```
Terraform will then initiate the cluster expansion process. The operation may take several minutes to complete, depending on the scale of the expansion.
4. You can monitor the progress of the cluster scaling operation by checking the Terraform output or by using the **Cluster Dashboard** on the StreamNative Cloud console.
5. To verify the status of your cluster after the operation, you can use the `terraform show` command or check the **Cluster Dashboard** on StreamNative Cloud console for the most up-to-date information on your cluster's resources and status.
Remember to always review the changes carefully before applying them to your production environment. It's recommended to test any scaling operations in a non-production environment first.