K8s: expand PVC

content/operate/kubernetes/re-clusters/expand-pvc.md

@@ -0,0 +1,90 @@
+---
+Title: Expand PersistentVolumeClaim (PVC)
+alwaysopen: false
+categories:
+- docs
+- operate
+- kubernetes
+description: Expand your persistent volume claim by editing the REC.
+linkTitle: Expand PVC
+weight: 15
+---
+
+This article outlines steps to increase the size of the persistent volume claim for your Redis Enterprise cluster (REC).
+
+[PersistentVolumeClaims (PVC)](https://kubernetes.io/docs/concepts/storage/persistent-volumes/#expanding-persistent-volumes-claims) are created by the Redis Enterprise operator and used by the RedisEnterpriseCluster (REC). PVCs are created with a specific size and [can be expanded](https://kubernetes.io/docs/concepts/storage/persistent-volumes/#expanding-persistent-volumes-claims) with the following steps, if the underlying [storage class](https://kubernetes.io/docs/concepts/storage/storage-classes/) supports it.
+
+This process involves deleting and recreating the REC StatefulSet with a larger persistent volume size. The pods owned by the StatefulSet are not restarted or affected by the deletion and recreation process, except when they are left without an owner momentarily.
+
+{{<note>}}Shrinking (reducing the size) of your PVC is not allowed. This process only allows you to expand (size up) your PVC.{{</note>}}
+
+## Prerequisites
+
+{{<warning>}}Do not change any other REC fields related to the StatefulSet while resizing is in progress.
+{{</warning>}}
+
+- PVC expansion must be supported and enabled by the StorageClass and underlying storage driver of the REC PVCs.
+  - The relevant StorageClass is the one associated with the REC PVCs. The StorageClass for existing PVCs cannot be changed.
+- The StorageClass must be configured with `allowVolumeExpansion: true`.
+- Your storage driver must support online expansion.
+- We highly recommend you backup your databases before beginning this PVC expansion process.
+
+## Expand REC PVC
+
+1. Enable the REC persistent volume resize flag.
+
+    ```YAML
+      spec:
+        persistentSpec:
+          enablePersistentVolumeResize: true
+    ```
+
+1. Set the value of `volumeSize` to your desired size.
+
+    ```YAML
+      spec:
+        persistentSpec:
+          enablePersistentVolumeResize: true
+          volumeSize: <new-size>
+    ```
+
+1. Apply the changes to the REC, replacing `<your-rec.yaml>` with the name of your REC.
+
+  ```sh
+  kubectl apply -f <your-rec.yaml>
+  ```
+
+After applying the REC changes, the PVCs will begin to expand to the new size.
+
+Once all the PVCs finish the resizing process, the operator will delete and recreate the StatefulSet with the new volume size.
+
+### Track progress
+
+You can track the progress by monitoring the status of the REC and PersistentVolumeClaim objects.
+
+The REC status will correspond to the status of one or more PVCs, and will reflect if the resizing is successful or failed.
+
+While the resizing is in progress, the status will be:
+
+```yaml
+status:
+  persistenceStatus:
+    status: Resizing
+    succeeded: 2/3
+```
+
+When the resizing is complete, the status becomes Provisioned and the new volume size is available for use by the REC pods.
+
+```yaml
+status:
+  persistenceStatus:
+    status: Provisioned
+    succeeded: 3/3
+```
+
+### Troubleshooting
+
+If an error occurs during this process:
+
+- Examine the status and events of the REC and PVC objects.
+- Examine the logs of the operator pods.