93 lines
2.8 KiB
Markdown
93 lines
2.8 KiB
Markdown
---
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title: Limit Storage Consumption
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content_template: templates/task
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---
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{{% capture overview %}}
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This example demonstrates an easy way to limit the amount of storage consumed in a namespace.
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The following resources are used in the demonstration: [ResourceQuota](/docs/concepts/policy/resource-quotas/),
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[LimitRange](/docs/tasks/administer-cluster/memory-default-namespace/),
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and [PersistentVolumeClaim](/docs/concepts/storage/persistent-volumes/).
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{{% /capture %}}
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{{% capture prerequisites %}}
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* {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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{{% /capture %}}
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{{% capture steps %}}
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## Scenario: Limiting Storage Consumption
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The cluster-admin is operating a cluster on behalf of a user population and the admin wants to control
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how much storage a single namespace can consume in order to control cost.
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The admin would like to limit:
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1. The number of persistent volume claims in a namespace
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2. The amount of storage each claim can request
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3. The amount of cumulative storage the namespace can have
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## LimitRange to limit requests for storage
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Adding a `LimitRange` to a namespace enforces storage request sizes to a minimum and maximum. Storage is requested
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via `PersistentVolumeClaim`. The admission controller that enforces limit ranges will reject any PVC that is above or below
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the values set by the admin.
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In this example, a PVC requesting 10Gi of storage would be rejected because it exceeds the 2Gi max.
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```
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apiVersion: v1
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kind: LimitRange
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metadata:
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name: storagelimits
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spec:
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limits:
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- type: PersistentVolumeClaim
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max:
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storage: 2Gi
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min:
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storage: 1Gi
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```
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Minimum storage requests are used when the underlying storage provider requires certain minimums. For example,
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AWS EBS volumes have a 1Gi minimum requirement.
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## StorageQuota to limit PVC count and cumulative storage capacity
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Admins can limit the number of PVCs in a namespace as well as the cumulative capacity of those PVCs. New PVCs that exceed
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either maximum value will be rejected.
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In this example, a 6th PVC in the namespace would be rejected because it exceeds the maximum count of 5. Alternatively,
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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
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for a namespace capped at 5Gi.
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```
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apiVersion: v1
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kind: ResourceQuota
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metadata:
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name: storagequota
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spec:
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hard:
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persistentvolumeclaims: "5"
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requests.storage: "5Gi"
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```
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{{% capture discussion %}}
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## Summary
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A limit range can put a ceiling on how much storage is requested while a resource quota can effectively cap the storage
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consumed by a namespace through claim counts and cumulative storage capacity. The allows a cluster-admin to plan their
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cluster's storage budget without risk of any one project going over their allotment.
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{{% /capture %}}
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