# Storage Configuration

## Prerequisites

Before deploying your SingleStore cluster, ensure that an appropriate `StorageClass` is available in your Kubernetes cluster. The `storageClass` value specified in `sdb-cluster.yaml` must match an existing `StorageClass` resource.

Run the following command to list available storage classes:

```shell
kubectl get storageclass
```

When selecting a `StorageClass` for SingleStore, verify the following properties.

* `allowVolumeExpansion`

  * Must be `true` for production deployments to enable online volume expansion
  * If `false`, storage size cannot be increased after deployment
* `reclaimPolicy`

  * `Delete` automatically removes `PersistentVolumes` when the cluster is deleted
  * `Retain` preserves data after cluster deletion, while `Delete` automatically cleans up volumes. Select the option that meets your operational requirements and data retention policies.
* `volumeBindingMode`

  * `Immediate` provisions the volume when the `PersistentVolumeClaim` is created
  * `WaitForFirstConsumer` delays provisioning until a pod is scheduled. SingleStore recommends this value for multi-zone deployments

To inspect a specific `StorageClass`:

```shell
kubectl describe storageclass <class-name>
```

Confirm that `allowVolumeExpansion` is set to `true` for production deployments.

If a suitable `StorageClass` is not available, create one with volume expansion enabled. Refer to Storage Class Objects for more information.

Apply the configuration:

```shell
kubectl apply -f storageclass.yaml
```

Before deploying the cluster, ensure the following:

* The `StorageClass` exists:
  ```shell
  kubectl get storageclass <class-name>
  ```
* The `StorageClass` has `allowVolumeExpansion` set to `true` for production deployments
* RBAC permissions are correctly configured in `sdb-rbac.yaml`

> **📝 Note**: The `StorageClass` must exist before running `kubectl apply -f sdb-cluster.yaml`. After deployment, changing the `StorageClass` requires backing up data, deleting the cluster, and redeploying it.

## Fault-Tolerant Storage Configuration

To deploy a fault-tolerant SingleStore cluster, configure the `redundancyLevel` and appropriate storage resources.

* `redundancyLevel: 1` disables replication and is intended for development or testing
* `redundancyLevel: 2` enables data replication and is required for production deployments

With `redundancyLevel: 2`, each partition has two replicas distributed across availability groups. A minimum of two leaf nodes is required; one node per availability group.

The following is a fault-tolerant configuration example:

```yaml
apiVersion: memsql.com/v1alpha1
kind: MemsqlCluster
metadata:
name: sdb-cluster-ha
spec:
license: license_key
adminHashedPassword: "hashed_password"
nodeImage:
repository: singlestore/node
tag: alma-9.1.0
redundancyLevel: 2
aggregatorSpec:
count: 3 # Use odd numbers such as 3, 5, or 7
cores: 8
coresLimit: 8
memoryMB: 32768
memoryLimitMB: 32768
storageGB: 256
storageClass: premium-rwo
leafSpec:
count: 4 # Four leaves create two availability groups
cores: 16
coresLimit: 16
memoryMB: 131072
memoryLimitMB: 131072
storageGB: 1024
storageClass: premium-rwo
```

Use an odd number of voting member aggregators - typically one Master Aggregator (MA) and two or more child aggregators (CAs) configured as voting members at the time the cluster is created - to maintain quorum for cluster consensus. For example:

* Three master aggregators tolerate one failure
* Five master aggregators tolerate two failures

For child aggregators, SingleStore recommends running at least two to maintain connectivity during cluster maintenance operations.

With `redundancyLevel: 2`, data is replicated across leaf nodes.

* Total usable storage is approximately`(leafSpec.count × leafSpec.storageGB)/ 2`
* For example, four leaf nodes with 1 TB each provide approximately 2 TB of usable storage

Refer to [Managing High Availability](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/high-availability-and-disaster-recovery/managing-high-availability.md) and [Disaster Recovery](https://docs.singlestore.com/db/v9.1/reference/singlestore-operator-reference/disaster-recovery.md) for more information.

***

Modified at: May 11, 2026

Source: [/db/v9.1/reference/singlestore-operator-reference/storage-configuration/](https://docs.singlestore.com/db/v9.1/reference/singlestore-operator-reference/storage-configuration/)

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