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Resource Quota Per VolumeAttributesClass
Signed-off-by: carlory <[email protected]>
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‎content/en/docs/concepts/policy/resource-quotas.md

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| `NotBestEffort` | Match pods that do not have best effort quality of service. |
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| `PriorityClass` | Match pods that references the specified [priority class](/docs/concepts/scheduling-eviction/pod-priority-preemption). |
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| `CrossNamespacePodAffinity` | Match pods that have cross-namespace pod [(anti)affinity terms](/docs/concepts/scheduling-eviction/assign-pod-node). |
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| `VolumeAttributesClass` | Match persistentvolumeclaims that references the specified [volume attributes class](/docs/concepts/storage/volume-attributes-classes). |
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The `BestEffort` scope restricts a quota to tracking the following resource:
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if the namespace where they are created have a resource quota object with
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`CrossNamespacePodAffinity` scope and a hard limit greater than or equal to the number of pods using those fields.
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### Resource Quota Per VolumeAttributesClass
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{{< feature-state feature_gate_name="VolumeAttributesClass" >}}
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PersistentVolumeClaims can be created with a specific [volume attributes class](/docs/concepts/storage/volume-attributes-classes/), and might be modified after creation. You can control a PVC's consumption of storage resources based on the associated volume attributes classes, by using the `scopeSelector` field in the quota spec.
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The PVC references the associated volume attributes class by the following fields:
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* `spec.volumeAttributesClassName`
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* `status.currentVolumeAttributesClassName`
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* `status.modifyVolumeStatus.targetVolumeAttributesClassName`
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A quota is matched and consumed only if `scopeSelector` in the quota spec selects the PVC.
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When quota is scoped for volume attributes class using `scopeSelector` field, quota object is restricted to track only following resources:
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* `persistentvolumeclaims`
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* `requests.storage`
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This example creates a quota object and matches it with PVC at specific volume attributes classes. The example works as follows:
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- PVCs in the cluster have at least one of the three volume attributes classes, "gold", "silver", "copper".
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- One quota object is created for each volume attributes class.
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Save the following YAML to a file `quota-vac.yaml`.
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{{% code_sample file="policy/quota-vac.yaml" %}}
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Apply the YAML using `kubectl create`.
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```shell
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kubectl create -f ./quota-vac.yaml
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```
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```
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resourcequota/pvcs-gold created
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resourcequota/pvcs-silver created
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resourcequota/pvcs-copper created
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```
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Verify that `Used` quota is `0` using `kubectl describe quota`.
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```shell
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kubectl describe quota
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```
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```
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Name: pvcs-gold
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 10Gi
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Name: pvcs-silver
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 20Gi
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Name: pvcs-copper
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 30Gi
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```
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Create a pvc with volume attributes class "gold". Save the following YAML to a file `gold-vac-pvc.yaml`.
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{{% code_sample file="policy/gold-vac-pvc.yaml" %}}
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Apply it with `kubectl create`.
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```shell
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kubectl create -f ./gold-vac-pvc.yaml
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```
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Verify that "Used" stats for "gold" volume attributes class quota, `pvcs-gold` has changed and that the other two quotas are unchanged.
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```shell
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kubectl describe quota
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```
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```
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Name: pvcs-gold
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 1 10
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requests.storage 2Gi 10Gi
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Name: pvcs-silver
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 20Gi
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Name: pvcs-copper
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 30Gi
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```
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Once the PVC is bound, it is allowed to modify the desired volume attributes class. Let's change it to "silver" with `kubectl patch`.
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```shell
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kubectl patch pvc gold-vac-pvc --type='merge' -p '{"spec":{"volumeAttributesClassName":"silver"}}'
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```
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Verify that "Used" stats for "silver" volume attributes class quota, `pvcs-silver` has changed, `pvcs-copper` is unchanged, and `pvcs-gold` might be unchanged or released, which depends on the PVC's status.
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```shell
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kubectl describe quota
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```
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```
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Name: pvcs-gold
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 1 10
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requests.storage 2Gi 10Gi
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Name: pvcs-silver
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 1 10
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requests.storage 2Gi 20Gi
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Name: pvcs-copper
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 30Gi
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```
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Wait a moment for the operation to complete, then verify the quota again.
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```shell
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kubectl describe quota
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```
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```
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Name: pvcs-gold
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 10Gi
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Name: pvcs-silver
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 1 10
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requests.storage 2Gi 20Gi
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Name: pvcs-copper
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Namespace: default
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Resource Used Hard
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-------- ---- ----
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persistentvolumeclaims 0 10
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requests.storage 0 30Gi
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```
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## Requests compared to Limits {#requests-vs-limits}
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When allocating compute resources, each container may specify a request and a limit value for either CPU or memory.

‎content/en/examples/policy/gold-vac-pvc.yaml

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apiVersion: v1
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kind: PersistentVolumeClaim
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metadata:
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name: gold-vac-pvc
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spec:
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accessModes:
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- ReadWriteOnce
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resources:
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requests:
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storage: 2Gi
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storageClassName: # change this to the name of the storage class you want to use
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volumeAttributesClassName: gold

‎content/en/examples/policy/quota-vac.yaml

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apiVersion: v1
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kind: List
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items:
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- apiVersion: v1
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kind: ResourceQuota
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metadata:
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name: pvcs-gold
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spec:
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hard:
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requests.storage: "10Gi"
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persistentvolumeclaims: "10"
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scopeSelector:
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matchExpressions:
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- operator: In
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scopeName: VolumeAttributesClass
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values: ["gold"]
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- apiVersion: v1
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kind: ResourceQuota
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metadata:
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name: pvcs-silver
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spec:
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hard:
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requests.storage: "20Gi"
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persistentvolumeclaims: "10"
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scopeSelector:
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matchExpressions:
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- operator: In
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scopeName: VolumeAttributesClass
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values: ["silver"]
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- apiVersion: v1
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kind: ResourceQuota
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metadata:
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name: pvcs-copper
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spec:
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hard:
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requests.storage: "30Gi"
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persistentvolumeclaims: "10"
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scopeSelector:
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matchExpressions:
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- operator: In
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scopeName: VolumeAttributesClass
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values: ["copper"]

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