Managing storage classes

The storage class (StorageClass) allows administrators to divide storages they provide into classes with defined parameters. Classes differ by the disk type and pricing policy.

Managed Service for Kubernetes has the following storage classes available that differ by the disk type:

• yc-network-hdd (default): Network HDD storage (network-hdd).
• yc-network-ssd: Network SSD storage (network-ssd).
• yc-network-ssd-nonreplicated: Enhanced performance non-replicated SSD storage (network-ssd-nonreplicated).
• yc-network-ssd-io-m3: Enhanced performance network SSD storage (network-ssd-io-m3).

Each storage is created with the following parameters:

• Volume Binding Mode: WaitForFirstConsumer.
• Reclaim Policy: Delete.

For these classes, you can only use PersistentVolumeClaim and PersistentVolume in ReadWriteOnce access mode.

You can create your own storage class as well as update the default storage class.

First, install kubectl and configure it to work with the Managed Service for Kubernetes cluster you created.

Create a storage classCreate a storage class

1. Save the storage class creation specification to a YAML file named my-sc-hdd.yaml:

   Learn more about the storage class creation specification format.

   kind: StorageClass
   apiVersion: storage.k8s.io/v1
   metadata:
     name: my-sc-hdd
   provisioner: disk-csi-driver.mks.ycloud.io
   volumeBindingMode: WaitForFirstConsumer
   parameters:
     type: network-hdd
     csi.storage.k8s.io/fstype: ext4
   allowVolumeExpansion: false
   reclaimPolicy: Retain
   

2. Run this command:

   kubectl create -f my-sc-hdd.yaml
   

   Result:

   storageclass.storage.k8s.io/my-sc-hdd created
   

3. Check that the storage class was created:

   kubectl get storageclass
   

   Result:

   NAME                      PROVISIONER                    AGE
   my-sc-hdd                 disk-csi-driver.mks.ycloud.io  76s
   yc-network-hdd (default)  disk-csi-driver.mks.ycloud.io  16m
   yc-network-ssd            disk-csi-driver.mks.ycloud.io  16m
   

Format of a storage class creation specificationFormat of a storage class creation specification

Each StorageClass object contains the parameters, allowVolumeExpansion, and reclaimPolicy properties used for dynamic allocation of PersistentVolume.

The structure of the YAML file is as follows:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: <storage_class_name> # Used to access a storage class.
provisioner: <provider_name>
volumeBindingMode: WaitForFirstConsumer
parameters: # Storage class parameters.
  type: <disk_type>
  csi.storage.k8s.io/fstype: <file_system_type>
allowVolumeExpansion: <allow_volume_expansion>
reclaimPolicy: <reclaim_policy>

The acceptable parameter values include:

• parameters:
  • type: network-hdd, network-ssd, network-ssd-nonreplicated, or network-ssd-io-m3.
  • csi.storage.k8s.io/fstype: ext2, ext3, or ext4.
• reclaimPolicy: Retain or Delete.
• allowVolumeExpansion: true or false.

Update the default storage classUpdate the default storage class

1. Check which storage class is set as default: next to its name, you will see default in a parenthesis.

   kubectl get storageclass
   

   Result:

   NAME                      PROVISIONER                    AGE
   my-sc-hdd                 disk-csi-driver.mks.ycloud.io  76s
   yc-network-hdd (default)  disk-csi-driver.mks.ycloud.io  16m
   yc-network-ssd            disk-csi-driver.mks.ycloud.io  16m
   

2. Change the storageclass.kubernetes.io/is-default-class parameter of the default storage class to false to remove its default class status:

   kubectl patch storageclass yc-network-hdd \
     -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"false"}}}'
   

3. Check that yc-network-hdd is no longer the default storage class:

   kubectl get storageclass
   

   Result:

   NAME            PROVISIONER                    AGE
   my-sc-hdd       disk-csi-driver.mks.ycloud.io  2m36s
   yc-network-hdd  disk-csi-driver.mks.ycloud.io  17m
   yc-network-ssd  disk-csi-driver.mks.ycloud.io  17m
   

4. Specify a new default storage class, e.g., my-sc-hdd:

   kubectl patch storageclass my-sc-hdd \
     -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'
   

5. Check that my-sc-hdd is the default storage class now:

   kubectl get storageclass
   

   Result:

   NAME                 PROVISIONER                    AGE
   my-sc-hdd (default)  disk-csi-driver.mks.ycloud.io  4m21s
   yc-network-hdd       disk-csi-driver.mks.ycloud.io  19m
   yc-network-ssd       disk-csi-driver.mks.ycloud.io  19m
   

See alsoSee also

• Volume
• Using encrypted disks for persistent volumes
• Dynamic volume provisioning
• Static volume provisioning