Add storage decrease instructions

and expand the instructions with mention of Helm-managed
clusters and a more detailed instructions for node replacement
procedure. Fix some typos and make the values more consistent.

docs/source/storage_resizing.md

@@ -1,8 +1,8 @@
 # Resizing storage in Scylla Cluster
 
-Due to limitations of the underlying StatefulSets, ScyllaClusters don't allow storage changes. The following procedure describes how to adjust the storage manually.
+Due to limitations of the underlying StatefulSet, ScyllaClusters don't allow storage changes. The following procedure describes how to adjust the storage manually.
 
-Let's use the following pods and statefulsets in the resize example below. 
+Let's use the following pods and StatefulSet in the resize examples below.
    ``` 
    kubectl get pods                                                      
                  
@@ -17,31 +17,34 @@ Let's use the following pods and statefulsets in the resize example below.
    simple-cluster-us-east-1-us-east-1a   3/3     12m
    ``` 
 
+
+## Increasing the storage size
+
 1. Orphan delete Scylla Cluster
     ```
     kubectl delete scyllacluster/simple-cluster --cascade='orphan'
    
     scyllacluster.scylla.scylladb.com "simple-cluster" deleted
     ```
-2. Orphan delete Statefulsets
+2. Orphan delete StatefulSet
     ```
     kubectl delete statefulset --selector scylla/cluster=simple-cluster --cascade='orphan'
    
     statefulset.apps "simple-cluster-us-east-1-us-east-1a" deleted
     ```
-3. Change storage request in PVCs
+3. Change storage request in PVCs.
     ```
-    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-0 -p '{"spec":{"resources":{"requests":{"storage":"2Gi"}}}}'
+    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-0 -p '{"spec":{"resources":{"requests":{"storage":"3Gi"}}}}'
     
     persistentvolumeclaim/data-simple-cluster-us-east-1-us-east-1a-0 patched
     ```
     ```
-    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-1 -p '{"spec":{"resources":{"requests":{"storage":"2Gi"}}}}'
+    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-1 -p '{"spec":{"resources":{"requests":{"storage":"3Gi"}}}}'
     
     persistentvolumeclaim/data-simple-cluster-us-east-1-us-east-1a-1 patched
     ```
     ```
-    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-2 -p '{"spec":{"resources":{"requests":{"storage":"2Gi"}}}}'
+    kubectl patch pvc/data-simple-cluster-us-east-1-us-east-1a-2 -p '{"spec":{"resources":{"requests":{"storage":"3Gi"}}}}'
     
     persistentvolumeclaim/data-simple-cluster-us-east-1-us-east-1a-2 patched
     ```
@@ -52,14 +55,45 @@ Let's use the following pods and statefulsets in the resize example below.
     
     Error from server (Forbidden): persistentvolumeclaims "data-simple-cluster-us-east-1-us-east-1a-0" is forbidden: only dynamically provisioned pvc can be resized and the storageclass that provisions the pvc must support resize
     ``` 
-    you need replace every node following the procedure described in [replacing nodes](nodeoperations/replace_node.md). 
+    then continue to step 4. 
 
-
-4. Apply updated ScyllaCluster definition 
+4. Apply updated ScyllaCluster definition with the new storage size in the `spec.datacenter.racks[0].storage.capacity` field:
    ```
    kubectl apply -f clusterDefinition.yaml --server-side=true
    ```
+   or, you use Helm to manage your Scylla Cluster, edit your values YAML with the cluster definition and its `racks[0].storage.capacity` field and apply the change with:
+   ```
+   helm upgrade simple-cluster scylla/scylla --values values.cluster.yaml
+   ```
+   The StatefulSet will be recreated by the Scylla Operator with the new storage size.
 
+5. (Only if PVC does not support volume expansion) You need to replace every Scylla node, one by one, following the procedure described in [replacing nodes](nodeoperations/replace_node.md). Start with the last node in the StatefulSet and move towards the first node. This will recreate each node and their PVCs with the new size.
+
+
+## Decreasing the storage size
+
+1. Orphan delete Scylla Cluster
+    ```
+    kubectl delete scyllacluster/simple-cluster --cascade='orphan'
+   
+    scyllacluster.scylla.scylladb.com "simple-cluster" deleted
+    ```
 
+2. Orphan delete Statefulset
+    ```
+    kubectl delete statefulset --selector scylla/cluster=simple-cluster --cascade='orphan'
+   
+    statefulset.apps "simple-cluster-us-east-1-us-east-1a" deleted
+    ```
 
+3. Apply updated ScyllaCluster definition with the new storage size in the `spec.datacenter.racks[0].storage.capacity` field.
+    ```
+    kubectl apply -f clusterDefinition.yaml --server-side=true
+    ```
+   or, if you use Helm to manage your Scylla Cluster, edit your values YAML with the cluster definition and its `racks[0].storage.capacity` field and apply the change with:
+    ```
+    helm upgrade simple-cluster scylla/scylla --values values.cluster.yaml
+    ```
+   The StatefulSet will be recreated by the Scylla Operator with the new storage size, but the actual change will NOT be automatically applied.
 
+4. You need to replace every Scylla node, one by one, following the procedure described in [replacing nodes](nodeoperations/replace_node.md). Start with the last node in the StatefulSet and move towards the first node. This will recreate each node and their PVCs with the new size.