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StorageClass (sc)

  • Storage Class (SC) provisions volumes dynamically (represented by a PV) whenever a PVC is created

  • What is Dynamic Provisioning?

  • Automatically creates the storage needed (locally or on cloud providers)
  • Differently from Static Provisioning (with static PVs) where the storage must be in place beforehand
  • With StorageClasses a provisioner is defined (E.g., google storage) that automatically provisions storage
  • When claiming a storage (with PVC associated with a SC), the PV is created automatically

Properties

allowVolumeExpansion

  • Expands the storage automatically
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/no-provisioner
allowVolumeExpansion: true

volumeBindingMode

  • Immediate (default)

  • SC creates a PV as soon as the PVC is created

  • WaitForFirstConsumer

  • SC creates a PV as soon as the PVC is created AND the pod initializes
  • Before the pod initializes the PVC remains in Pending state
  • This way the PV is provisioned in the same region of the pod
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

spec.allowedTopologies

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ebs-sc
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer
parameters:
  csi.storage.k8s.io/fstype: xfs
  type: io1
  iopsPerGB: "50"
  encrypted: "true"
allowedTopologies:
  - matchLabelExpressions:
    - key: topology.kubernetes.io/zone
      values:
        - us-east-2c

provisioner

kubernetes.io/no-provisioner

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/no-provisioner

kubernetes.io/gce-pd

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-standard # pd-ssd
  replication-type: none # regional-pd

kubernetes.io/aws-ebs

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/aws-ebs
parameters:
  type: io1
  iopsPerGB: "10"
  fsType: ext4

kubernetes.io/azure-disk

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: managed
provisioner: kubernetes.io/azure-disk # Disk PV can only be attached to one pod at a time
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
parameters:
  kind: Managed # Shared (default), Managed, Dedicated
  storageaccounttype: StandardSSD_LRS # Premium_LRS, Standard_LRS
  cachingmode: ReadOnly

kubernetes.io/azure-file

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azurefile # /usr/share/nginx/html to serve pages
provisioner: kubernetes.io/azure-file # File Shares can be attached to multiple pods at the same time
reclaimPolicy: Delete
volumeBindingMode: Immediate
allowVolumeExpansion: true
parameters:
  skuName: Standard_LRS
mountOptions:
  - dir_mode=0777
  - file_mode=0777
  - uid=0
  - gid=0
  - mfsymlinks
  - cache=strict
  - actimeo=30

ebs.csi.aws.com

  • Requires the EBS CSI Driver installed on the cluster
  • By default when creating an EKS cluster only a kubernetes.io/aws-ebs storage class is created
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ebs-sc
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer
parameters:
  csi.storage.k8s.io/fstype: xfs
  type: io1
  iopsPerGB: "50"
  encrypted: "true"
  # fstype: ntfs # for windows
allowedTopologies:
  - matchLabelExpressions:
    - key: topology.kubernetes.io/zone
      values:
        - us-east-2c

reclaimPolicy (bypass)

  • Bypassed to pv.spec.persistentVolumeReclaimPolicy
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: my-sc
provisioner: kubernetes.io/no-provisioner
reclaimPolicy: Retain