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Yandex Managed Service for Kubernetes

Managing storage classes

Storage class (StorageClass) allows administrators to divide the stores they provision into classes with defined parameters.

Managed Service for Kubernetes automatically provides two storage classes, yc-network-hdd and yc-network-ssd, with the following parameters:

These classes only let you use PersistentVolumeClaims and PersistentVolumes in access mode ReadWriteOnce.

Classes differ based on the type of disk created:

  • yc-network-hdd uses a standard network drive (network-hdd).
  • yc-network-ssd uses a fast network drive (network-ssd).

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

Note

yc-network-nvme is deprecated. Use yc-network-ssd instead.

Create a storage class

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

    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 the command:

    $ kubectl create -f my-sc-hdd.yaml
storageclass.storage.k8s.io/my-sc-hdd created

  3. Check that the storage class was created:

    $ kubectl get storageclass
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

Specification format for creating a storage class

Each StorageClass object contains the provisioner, parameters, and reclaimPolicy parameters that are used for the dynamic provisioning of PersistentVolumes.

Acceptable parameter values:

  • provisioner: disk-csi-driver.mks.ycloud.io.
  • parameters
    • type: network-hdd or network-ssd.
    • csi.storage.k8s.io/fstype: ext2, ext3, or ext4.
  • reclaimPolicy: Retain or Delete.

YAML file structure:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: <storage class name> # Used for accessing the storage class.
provisioner: <provisioner name>
volumeBindingMode: WaitForFirstConsumer
parameters: # Storage class parameters.
  type: <disk type>
  csi.storage.k8s.io/fstype: <file system type>
allowVolumeExpansion: false
reclaimPolicy: <reclaim policy>

Change the default storage class

  1. Look up which storage class is assigned by default. default is shown next to its name in parentheses.

    $ kubectl get storageclass
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 status as the default class:

    $ 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
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, such as 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:

    $ kubectl get storageclass
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
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