added storage limit example

_data/guides.yml

@@ -189,6 +189,7 @@ toc:
   - docs/admin/disruptions.md
   - docs/admin/resourcequota/index.md
   - docs/admin/resourcequota/walkthrough.md
+  - docs/admin/resourcequota/limitstorageconsumption.md
   - docs/admin/rescheduler.md
   - docs/admin/sysctls.md
   - docs/admin/cluster-components.md

docs/admin/resourcequota/limitstorageconsumption.md

@@ -0,0 +1,75 @@
+---
+---
+
+This example demonstrates an easy way to limit the amount of storage consumed in a namespace.
+
+The following resources are used in the demonstration:
+
+* [Resource Quota](/docs/admin/resourcequota/)
+* [Limit Range](/docs/admin/limitrange/)
+* [Persistent Volume Claim](/docs/user-guide/persistent-volumes/)
+
+This example assumes you have a functional Kubernetes setup.
+
+## Scenario
+
+The cluster-admin is operating a cluster on behalf of a user population and the admin wants to control
+how much storage a single namespace can consume in order to control cost.
+
+The admin would like to limit:
+
+1. The number of persistent volume claims in a namespace
+2. The amount of storage each claim can request
+3. The amount of cumulative storage the namespace can have
+
+
+## LimitRange to limit requests for storage
+
+Adding a `LimitRange` to a namespace enforces storage request sizes to a minimum and maximum. Storage is requested
+via `PersistentVolumeClaim`. The admission controller that enforces limit ranges will reject any PVC that is above or below
+the values set by the admin.
+
+In this example, a PVC requesting 10Gi of storage would be rejected because it exceeds the 2Gi max.
+
+```
+apiVersion: v1
+kind: LimitRange
+metadata:
+  name: storagelimits
+spec:
+  limits:
+  - type: PersistentVolumeClaim
+    max:
+      storage: 2Gi
+    min:
+      storage: 1Gi
+```
+
+Minimum storage requests are used when the underlying storage provider requires certain minimums. For example, 
+AWS EBS volumes have a 1Gi minimum requirement. 
+
+## StorageQuota to limit PVC count and cumulative storage capacity
+
+Admins can limit the number of PVCs in a namespace as well as the cumulative capacity of those PVCs. New PVCs that exceed
+either maximum value will be rejected.
+
+In this example, a 6th PVC in the namespace would be rejected because it exceeds the maximum count of 5. Alternatively, 
+a 5Gi maximum quota when combined with the 2Gi max limit above, cannot have 3 PVCs where each has 2Gi. That would be 6Gi requested
+ for a namespace capped at 5Gi. 
+
+```
+apiVersion: v1
+kind: ResourceQuota
+metadata:
+  name: storagequota
+spec:
+  hard:
+    persistentvolumeclaims: "5"
+    requests.storage: "5Gi"
+```
+
+## Summary 
+
+A limit range can put a ceiling on how much storage is requested while a resource quota can effectively cap the storage
+consumed by a namespace through claim counts and cumulative storage capacity. The allows a cluster-admin to plan their 
+cluster's storage budget without risk of any one project going over their allotment.