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Manage Storage Volumes

How to manage Storage Volumes as Persistent Volumes on CKS

On CKS, Storage Volumes are created as Persistent Volumes (PVs), by deploying Persistent Volume Claims (PVCs).

Specifying the type, size, and placement of Storage Volumes is accomplished by configuring the manifest for the Persistent Volume Claim.

Persistent Volume Claims​

Persistent Volume Claims are requests for Persistent Volume resources, which are used as storage volumes for workloads that require persistent storage for workloads.

Create PVCs​

Create a PVC by clicking the PVC icon in the Cloud Console sidebar, or via the API by deploying a PVC manifest.

Create a PVC using the API​

Create a Persistent Volume Claim by annotating the following YAML manifest to your specifications:

Example
apiVersion: v1

kind: PersistentVolumeClaim

metadata:

  name: new-pvc

  namespace: default

spec:

  accessModes:

    - ReadWriteOnce

  resources:

    requests:

      storage: 1Gi

  storageClassName: shared-vast

Update these fields in the manifest:

Field nameField typeDescription
namestringThe name of the PVC.
namespacestringThe namespace for the PVC.
spec.accessModeslistSets the access mode for the volume. Distributed Filesystem Volumes use ReadWriteMany.
resources.requests.storagestringDetermines the size of the volume, in Gi
storageClassNamestringThe storage class name is shared-vast for CKS.

Configure the manifest as desired, save it to a .yaml file, and apply it with kubectl:

Example
$
kubectl apply -f my-pvc.yaml

To verify that the PVC is bound to a PV, run:

Example
$
kubectl get pvc my-pvc

Output:

Example
NAME     STATUS   VOLUME                                 CAPACITY   ACCESS MODES   STORAGECLASS   AGE

my-PVC   Bound    pvc-b657b567-e-6b78-98347-67894349850  512Gi      RWO            shared-vast    1d

If desired, users can get more detailed information about the PVCs they have created by running the following command:

Example
$
kubectl describe pvc my-pvc

Create a PVC with the Cloud Console​

If no clusters exist, or the user has no access to any clusters, the following message is shown on the PVC dashboard.

If an active cluster is available, choose Create a PVC to begin.

Enter details for the PVC, then click Create. After the PVC is created, basic information about the PVC, including its name, age, size, and status is shown.

Working with PVCs​

The groups a user belongs to dictate the way they interact with PVC resources. Non-admin users may add PVCs through the UI or using the API, but their capacity to access and edit them is limited to their permitted actions within their clusters.

Administrators have comparatively greater powers over PVC resources. Users with admin, write, and read Cluster RoleBindings can add and remove PVCs from the groups they are in. In addition to this, the default admin privileges allows them to manage those PVCs collectively. They can also use the following Console Actions inside their cluster:

  • Edit RoleBindings.
  • Create and modify RBAC schemes which allow a chosen group or groups access to resources. These can be as general as a resource type, or as specific as a particular PVC.

Editing Volumes​

To edit a PVC, click the three-dot menu on the far right of the PVCs listing on the Overview page, then click Edit. Enter the desired changes in the pop-up modal.

Cloning PVCs​

Users with write permissions may clone PVCs.

Click the Clone button from the PVC's three-dot menu, and then enter a new name for the cloned PVC. Click Confirm to provision an exact copy of the PVC in the user's default namespace.

Delete a Storage Volume via the Cloud Console​

Info

Only users with admin permissions can delete Storage Volumes.

From the three-dot menu, select Delete.

When a PVC is deleted, any PV linked to it is automatically soft-deleted. Soft-deleted PVs are deleted permanently after the soft delete window (24hrs after the original PVC deletion) expires. To delete a PVC, type the name of the desired volume in the confirmation modal, then click Delete.

The volume is removed from the PVC overview menu when deletion is complete.

Persistent Volume Management Operator​

CKS features a Persistent Volume Management Operator (PVMO). PVMO is a Kubernetes controller manager that runs periodically to clean up orphaned volumes.

PVMO tracks PVC delete events through admission webhooks. If it finds a delete event, it adds the label pv-failsafe.coreweave.cloud/<deletion-timestamp> - where deletion-timestamp is the current time - to the Persistent Volume to which the PVC was attached.

The PVMO also adds a watcher service that periodically lists all Persistent Volumes in the cluster.

Info

By default, the watcher lists all PVs in the cluster once per hour.

The watcher service checks for any "orphaned" PVs. A PV is considered "orphaned" if it has been released from its PVC and does not have the soft delete label described above. If the watcher finds an orphaned PV, it adds the soft delete label to it.

The watcher service also checks Persistent Volumes to see if they are eligible for deletion. To be eligible, a PV must feature the soft delete label, and must have exceeded the soft delete window.

Info

The default soft delete window for PVs is 24 hours.

If both of these conditions are met, the PVMO updates the reclaim policy on the PV from Retain to Delete. This update means that the PV gets reclaimed by CKS and all of its underlying volumes are deleted.

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