# 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](../../../compute/concepts/disk.md#disks_types) and pricing policy. {% note alert %} The storage usage cost depends on its [disk](../../../compute/concepts/disk.md) type. Check out the [Yandex Compute Cloud disk prices](../../../compute/concepts/disk.md#disks_types) before creating a storage. {% endnote %} Managed Service for Kubernetes has the following storage classes available that differ by the [disk type](../../../compute/concepts/disk.md#disks_types): * `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`). {% note alert %} Non-replicated disks have no redundancy. If a disk fails, its data will be permanently lost. Learn more in [Non-replicated disks and ultra high-speed network storages with three replicas (SSD)](../../../compute/concepts/disk.md#nr-disks). {% endnote %} Each storage is created with the following parameters: * [Volume Binding Mode](https://kubernetes.io/docs/concepts/storage/storage-classes/#volume-binding-mode): `WaitForFirstConsumer`. * [Reclaim Policy](https://kubernetes.io/docs/concepts/storage/storage-classes/#reclaim-policy): `Delete`. For these classes, you can only use `PersistentVolumeClaim` and `PersistentVolume` in `ReadWriteOnce` [access mode](https://kubernetes.io/docs/concepts/storage/persistent-volumes/#access-modes). You can [create your own storage class](#sc-create) as well as [update the default storage class](#sc-default). First, [install kubectl](https://kubernetes.io/ru/docs/tasks/tools/install-kubectl/) and [configure it to work with the Managed Service for Kubernetes cluster you created](../connect/index.md#kubectl-connect). {% note info %} The `yc-network-nvme` class is deprecated; use `yc-network-ssd` instead. {% endnote %} ## Create a storage class {#sc-create} 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](#sc-spec). ```yaml 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 ``` 1. Run this command: ```bash kubectl create -f my-sc-hdd.yaml ``` Result: ```text storageclass.storage.k8s.io/my-sc-hdd created ``` 1. Check that the storage class was created: ```bash kubectl get storageclass ``` Result: ```text 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 specification {#sc-spec} 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: ```yaml kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: # Used to access a storage class. provisioner: volumeBindingMode: WaitForFirstConsumer parameters: # Storage class parameters. type: csi.storage.k8s.io/fstype: blockSize: "" allowVolumeExpansion: reclaimPolicy: ``` 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`, `ext4`, or `btrfs`. * `blockSize`: `4096`, `8192`, `16384`, `32768`, `65536`, `131072`. By default, the block size is 4096 KB for all new disks. For more information, see the section on [creating an empty disk with a large block size](../../../compute/operations/disk-create/empty-disk-blocksize.md). * `reclaimPolicy`: `Retain` or `Delete`. * `allowVolumeExpansion`: `true` or `false`. ## Update the default storage class {#sc-default} 1. Check which storage class is set as default: next to its name, you will see `default` in a parenthesis. ```bash kubectl get storageclass ``` Result: ```text 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 ``` 1. Change the `storageclass.kubernetes.io/is-default-class` parameter of the default storage class to `false` to remove its default class status: ```bash kubectl patch storageclass yc-network-hdd \ -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"false"}}}' ``` 1. Check that `yc-network-hdd` is no longer the default storage class: ```bash kubectl get storageclass ``` Result: ```text 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 ``` 1. Specify a new default storage class, e.g., `my-sc-hdd`: ```bash kubectl patch storageclass my-sc-hdd \ -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}' ``` 1. Check that `my-sc-hdd` is the default storage class now: ```bash kubectl get storageclass ``` Result: ```text 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 also {#see-also} * [Volume](../../concepts/volume.md) * [Using encrypted disks for persistent volumes](encrypted-disks.md) * [Dynamic volume provisioning](dynamic-create-pv.md) * [Static volume provisioning](static-create-pv.md)