Limit Storage Consumption [page]deterministic

This example demonstrates how to limit the amount of storage consumed in a namespace.

The following resources are used in the demonstration: [ResourceQuota](/docs/concepts/policy/resource-quotas/), [LimitRange](/docs/tasks/administer-cluster/manage-resources/memory-default-namespace/), and [PersistentVolumeClaim](/docs/concepts/storage/persistent-volumes/).

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## Scenario: Limiting Storage Consumption

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.

```yaml 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.

## ResourceQuota 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.

```yaml 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.