Configure Storage in the Helm Chart

Redpanda brokers must store their data on disk. You can customize the Helm chart to use the following storage types:

• PersistentVolumes
• hostPath volumes
• emptyDir volumes

By default, the Redpanda Helm chart uses the default StorageClass in a Kubernetes cluster to create one PersistentVolumeClaim for each Pod that runs a Redpanda broker. The default StorageClass in your Kubernetes cluster depends on the Kubernetes platform that you are using.

Prerequisites

If you're configuring Redpanda for production, make sure to review the storage best practices.

Use PersistentVolumes

A PersistentVolume is storage in the cluster that has been provisioned by an administrator or dynamically provisioned using StorageClasses. For details about PersistentVolumes, see the Kubernetes documentation.

You can configure the Helm chart to use PersistentVolumes with a static provisioner or a dynamic provisioner. Redpanda recommends using a StorageClass with a dynamic provisioner. See the best practices.

• storage.persistentVolume.storageClass sets the StorageClass that the Helm chart configures for each PersistentVolumeClaim.
• storage.persistentVolume.size sets the amount of resources that is requested by each PersistentVolumeClaim.
• storage.persistentVolume.labels sets the labels to apply to each PersistentVolumeClaim.
• storage.persistentVolume.annotations sets the annotations to apply to each PersistentVolumeClaim.

Dynamic provisioners

When you use a dynamic provisioner, it creates a PersistentVolume on demand for each Redpanda broker.

Managed Kubernetes platforms and cloud environments usually provide a dynamic provisioner. If you are running Kubernetes on-premise, you may need to deploy a dynamic provisioner for your storage type.

1. Make sure that you have at least one StorageClass in the cluster:

   kubectl get storageclass
   Example output

   In a Google GKE cluster, this is the result:

   NAME                 PROVISIONER            AGE
   standard (default)   kubernetes.io/gce-pd   1d

   This StorageClass is marked as the default, which means that this class is used to provision a PersistentVolume when the PersistentVolumeClaim doesn’t specify the StorageClass.

2. Configure the Helm chart with your StorageClass:

• To use your Kubernetes cluster's default StorageClass set storage.persistentVolume.storageClass to an empty string (""):

  --values

  storageclass.yaml

  storage:
    persistentVolume:
      enabled: true
      size: 20Gi
      storageClass: ""

  helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
    --values storageclass.yaml

  --set

  helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
    --set storage.persistentVolume.enabled=true \
    --set storage.persistentVolume.storageClass=""

• To use a specific StorageClass, set its name in the storage.persistentVolume.storageClass configuration:

  --values

  storageclass.yaml

  storage:
    persistentVolume:
      enabled: true
      size: 20Gi
      storageClass: "<storage-class>"

  helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
    --values storageclass.yaml

  --set

  helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
    --set storage.persistentVolume.enabled=true \
    --set storage.persistentVolume.storageClass="<storage-class>"

Static provisioners

When you use a static provisioner, an existing PersistentVolume in the cluster is selected and bound to one PersistentVolumeClaim for each Redpanda broker.

1. Create one PersistentVolume for each Redpanda broker. Make sure to create PersistentVolumes with a capacity of at least the value of the storage.persistentVolume.size configuration.

2. Set the storage.persistentVolume.storageClass to a dash ("-") to use a PersistentVolume with a static provisioner:

   --values

   storageclass.yaml

   storage:
     persistentVolume:
       enabled: true
       storageClass: "-"

   helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
     --values storageclass.yaml

   --set

   helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
     --set storage.persistentVolume.enabled=true \
     --set storage.persistentVolume.storageClass="-"

Resize PersistentVolumes

To give Redpanda brokers more storage, you can expand the size of PersistentVolumes. The way you expand PersistentVolumes depends on the provisioner that you use.

Dynamic provisioners

1. Make sure that your StorageClass is capable of volume expansions. For a list of volumes that support volume expansion, see the Kubernetes documentation.

2. Increase the value of the storage.persistentVolume.size configuration:

   --values

   persistentvolume-size.yaml

   storage:
     persistentVolume:
       enabled: true
       size: <custom-size>Gi

   helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
     --values persistentvolume-size.yaml

   --set

   helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
     --set storage.persistentVolume.enabled=true \
     --set storage.persistentVolume.size=<custom-size>Gi

Static provisioners

The instructions for resizing PersistentVolumes vary depending on the way the your filesystem is allocated. Follow the recommended process for your system. You do not need to make any configuration changes to the Helm chart.

Delete PersistentVolumeClaims

To prevent accidental loss of data, PersistentVolumesClaims are not deleted when Redpanda brokers are removed from a cluster. It is your responsibility to delete PersistentVolumeClaims when they are no longer needed. Check the reclaim policy of your PersistentVolumes before deleting a PersistentVolumeClaim.

kubectl get persistentvolume -n redpanda

For descriptions of each reclaim policy, see the Kubernetes documentation.

Use hostPath volumes

A hostPath volume mounts a file or directory from the host node's file system into your Pod. For details about hostPath volumes, see the Kubernetes documentation.

To store Redpanda data in hostPath volumes, set the storage.hostPath configuration to the absolute path of a file on the local worker node, and set storage.persistentVolume.enabled to false.

Use only for development and testing

If the Pod is deleted and recreated, it might be scheduled on another worker node and no longer have access to the same hostPath volume data.

--values

hostpath.yaml

storage:
  hostPath: "<absolute-path>"
  persistentVolume:
    enabled: false

helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
  --values hostpath.yaml

--set

helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
  --set storage.persistentVolume.enabled=false \
  --set storage.hostPath=<absolute-path>

Use emptyDir volumes

An emptyDir volume is first created when a Pod is assigned to a node, and the volume exists as long as the Pod is running on that node. For details about emptyDir volumes, see the Kubernetes documentation.

To store Redpanda data in emptyDir volumes, set the storage.hostPath configuration to an empty string (""), and set storage.persistentVolume.enabled to false.

Use only for development and testing

When a Pod is removed from a node for any reason, the data in the emptyDir volume is deleted permanently.

--values

emptydir.yaml

storage:
  hostPath: ""
  persistentVolume:
    enabled: false

helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
  --values emptydir.yaml

--set

helm upgrade --install redpanda redpanda/redpanda -n redpanda --create-namespace \
  --set storage.persistentVolume.enabled=false

Next steps

Enable rack awareness to minimize data loss in the event of a rack failure.