Volume Expansion for ClickHouse

Volume expansion increases the storage allocated to ClickHouse pods. The underlying StorageClass must support volume expansion.

Prerequisites

• A functional Kubernetes cluster (v1.21+ recommended)
• kubectl v1.21+ installed and configured with cluster access
• KubeBlocks installed (installation guide)
• ClickHouse Add-on enabled
• A demo namespace: kubectl create ns demo

kubectl get storageclass

Expand the ClickHouse Data Volume

kubectl apply -f - <<EOF
apiVersion: operations.kubeblocks.io/v1alpha1
kind: OpsRequest
metadata:
  name: clickhouse-volumeexpansion
  namespace: demo
spec:
  clusterName: clickhouse-cluster
  type: VolumeExpansion
  volumeExpansion:
    - componentName: clickhouse
      volumeClaimTemplates:
        - name: data
          storage: 20Gi
EOF

Monitor progress:

kubectl get opsrequest clickhouse-volumeexpansion -n demo -w

NAME                        TYPE              CLUSTER              STATUS    PROGRESS   AGE
clickhouse-volumeexpansion  VolumeExpansion   clickhouse-cluster   Succeed   1/1        60s

Verify the new storage size:

kubectl get pvc -n demo -l app.kubernetes.io/instance=clickhouse-cluster

Expand the Keeper Data Volume

For clusters using the cluster topology:

kubectl apply -f - <<EOF
apiVersion: operations.kubeblocks.io/v1alpha1
kind: OpsRequest
metadata:
  name: clickhouse-volumeexpansion-keeper
  namespace: demo
spec:
  clusterName: clickhouse-cluster
  type: VolumeExpansion
  volumeExpansion:
    - componentName: ch-keeper
      volumeClaimTemplates:
        - name: data
          storage: 20Gi
EOF

Cleanup

kubectl delete opsrequest clickhouse-volumeexpansion clickhouse-volumeexpansion-keeper -n demo --ignore-not-found