Configuring Storage Classes

1. Creating StorageClass

Field	Description	Example Value
apiVersion	API version of the StorageClass resource	`storage.k8s.io/v1`
kind	Kind of the Kubernetes resource	`StorageClass`
metadata.name	Name of the StorageClass	`fast-ssd`
provisioner	Driver used to provision storage (e.g., `kubernetes.io/aws-ebs`)	`aws.ebs.csi.driver`
reclaimPolicy	Policy for reclaiming storage after PVC is deleted	`Retain` or `Delete`
volumeBindingMode	When to bind volumes to pods	`Immediate` or `WaitForFirstConsumer`

Example: Creating a StorageClass for AWS EBS

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: aws.ebs.csi.driver
parameters:
  type: gp2
  fsType: ext4
reclaimPolicy: Retain
volumeBindingMode: WaitForFirstConsumer

2. Listing StorageClasses

Field	Description	Example Value
metadata.name	Name of the StorageClass	`fast-ssd`
provisioner	Driver used to provision storage	`kubernetes.io/aws-ebs`
reclaimPolicy	Policy for reclaiming storage after PVC is deleted	`Retain` or `Delete`
volumeBindingMode	When to bind volumes to PersistentVolumes	`Immediate` or `WaitForFirstConsumer`

Example: List StorageClasses using kubectl

kubectl get storageclass

Example: List StorageClasses with detailed output

kubectl get storageclass -o wide

3. Setting Default StorageClass

Field	Description	Value
metadata.name	Name of the StorageClass	`standard`
metadata.annotations	Annotations to set on the StorageClass	`{"storageclass.kubernetes.io/is-default-class": "true"}`
provisioner	Provisioner plugin used to create volumes	`kubernetes.io/aws-ebs`

Example: Setting Default StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2

Note: Setting a StorageClass as default means that any PersistentVolumeClaim (PVC) without a storageClassName specified will automatically use this StorageClass for volume provisioning.

4. Configuring Provisioners

Provisioner	Description	Supported Parameters	Notes
kubernetes.io/aws-ebs	Provisions EBS volumes for AWS clusters	`type`, `fsType`, `volumeID`	Requires AWS credentials and IAM permissions
kubernetes.io/azure-disk	Provisions Azure disks for AKS clusters	`cachingMode`, `diskSizeGB`, `fsType`	Requires Azure service principal credentials
kubernetes.io/gce-pd	Provisions GCP persistent disks for GKE clusters	`type`, `fsType`, `diskSizeGb`	Requires GCP service account with appropriate permissions
kubernetes.io/ibm-cloud-block-storage	Provisions IBM Cloud Block Storage volumes	`volumeType`, `zone`, `fsType`	Requires IBM Cloud API key and cluster access
kubernetes.io/vsphere	Provisions vSphere volumes for VMware clusters	`storagePolicyName`, `fsType`, `diskSizeGB`	Requires vCenter credentials and storage policy configuration

Example: Configuring AWS EBS Provisioner

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  fsType: ext4

Example: Configuring GCP PD Provisioner

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gcp-ssd
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-ssd
  fsType: ext4

5. Setting Volume Binding Mode

Binding Mode	Description	Use Case
Immediate	Volume is bound when the PersistentVolumeClaim (PVC) is created.	When you need the volume to be ready immediately for use by a Pod.
WaitForFirstConsumer	Volume is bound only when a Pod requests it.	When you want to defer binding until the PVC is actually used by a Pod, allowing for better scheduling decisions.

Example: Setting Volume Binding Mode in StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: aws-ebs
volumeBindingMode: WaitForFirstConsumer
parameters:
  type: gp2
  fsType: ext4

Note: The volumeBindingMode field is available in Kubernetes v1.10+.

6. Configuring Reclaim Policy

Policy	Description	Behavior	Notes
Retain	Manual cleanup required	Storage volume remains after PVC is deleted	Admin must manually delete the volume to reclaim storage
Delete	Automatic cleanup	Storage volume is deleted when PVC is deleted	Default for dynamically provisioned volumes in most cloud providers
Recycle	Deprecated	Obsolete method to reclaim storage (not supported in newer versions)	DEPRECATED in Kubernetes v1.5+

Example: Setting Reclaim Policy in StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: aws-ebs
parameters:
  type: gp2
reclaimPolicy: Retain
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Note: Reclaim policy affects how volumes are handled when the associated PersistentVolumeClaim (PVC) is deleted. Choose Retain if you need to preserve data for later use or migration.

7. Enabling Volume Expansion

Property	Description	Values	Notes
allowVolumeExpansion	Enables or disables volume expansion	`true` / `false`	Default is `false`. Set to `true` to allow expansion of volumes

Example: Enabling Volume Expansion in StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-storage
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
allowVolumeExpansion: true
reclaimPolicy: Retain

Note: Volume expansion is supported only for certain volume types (e.g., AWS EBS, GCP PD). Ensure that the underlying storage provider supports expansion.

8. Using Storage Parameters

Parameter	Description	Values	Notes
provisioner	Storage provisioner to use	`kubernetes.io/aws-ebs`, `awsEFS`, `gcePersistentDisk`	Must match the provisioner in the storage class
type	Storage type (e.g., SSD, HDD)	`gp2`, `io1`, `standard`	Used for AWS EBS volumes
fsType	File system type to use	`ext4`, `xfs`	Default is `ext4`
volumeBindingMode	When to bind volumes to pods	`Immediate`, `WaitForFirstConsumer`	`Immediate` binds at creation; `WaitForFirstConsumer` delays binding until pod is scheduled
reclaimPolicy	What happens to volume after PVC is deleted	`Retain`, `Recycle`, `Delete`	`Delete` is default for dynamically provisioned volumes

Example: Storage Class with Parameters

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  fsType: ext4
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Delete

9. Configuring Mount Options

Option	Description	Values	Notes
mountOptions	Mount options for the volume	`array`	Array of mount options to be passed to the volume plugin

Example: Setting Mount Options in StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: example-storageclass
provisioner: kubernetes.io/aws-ebs
mountOptions:
  - <span class="highlight">hard</span>
  - <span class="highlight">nfsvers=4.1</span>
parameters:
  type: gp2

Note: Mount options are specific to the volume plugin and must be supported by the underlying storage system.

10. Deleting StorageClasses

Property	Description	Notes
name	Name of the StorageClass to delete	Must be unique within the cluster
cascade	Whether to delete dependent resources	Default is `background`

Example: Delete StorageClass

kubectl delete storageclass standard

Note: Ensure no PersistentVolumeClaims are bound to volumes managed by this StorageClass before deletion.

Warning: Deleting a StorageClass that is in use may cause data loss or disruption to running workloads.