> ## Documentation Index
> Fetch the complete documentation index at: https://docs.scitix.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview of persistent storage for CKS clusters

> Understand the relationship between PVs, PVCs, and StorageClasses, and choose dynamic or static volumes.

CKS clusters use Kubernetes persistent volumes to store workload data. If training data, model files, or task output must be retained after Pods are rebuilt, first prepare persistent storage, then use a PVC to mount the storage to the workload.

## Learn about persistent storage objects

| Object | Description | Scope |
| - | - | - |
| PV (PersistentVolume) | Represents a piece of persistent storage available for use by a cluster. A PV includes information such as capacity, access modes, reclaim policy, and storage backend. | Cluster level |
| PVC (PersistentVolumeClaim) | Represents a workload's request for storage capacity and Access Method. Workloads use PVs through PVCs rather than referencing PVs directly. | Namespace level |
| StorageClass | Defines how storage volumes are dynamically created, including the storage plugin, reclaim policy, and storage parameters. | Cluster level |

After a PVC is bound to an eligible PV, its status changes to `Bound`. A workload can reference only PVCs in the same namespace.

## Select how to use a storage volume

Depending on whether the backend storage is ready, choose a dynamic storage volume or a static storage volume.

| Method | Applicable scenario | Resource relationship | Required preparations |
| - | - | - | - |
| Dynamic volumes | You want PVs to be created automatically based on PVC requests. | StorageClass → PVC → Automatically created PV | An available storage plugin and StorageClass. When using GPFS, you can also create a StorageClass through a volume template. |
| Static volumes | The backend storage already exists, or storage resources need to be prepared in advance by a storage administrator. | Backend storage → Manually created PV → PVC | Backend storage information and a PV configuration that matches the storage. |

StorageClass is the core object for dynamically provisioning storage volumes. When using static storage volumes, you can also match PVs and PVCs through `storageClassName`, but StorageClass will not automatically create PVs.

## Using persistent storage

1. Depending on how the Volume is prepared, create or bind a storage volume:

   * [Use Dynamic Persistent Volumes](https://docs.scitix.ai/gpu-cloud/cluster/use-dynamic-persistent-volume.md)
   * [Use Static Persistent Volumes](https://docs.scitix.ai/gpu-cloud/cluster/use-static-persistent-volume.md)

2. Verify that the PVC status is `Bound`.

3. [Mount persistent storage to a workload](https://docs.scitix.ai/gpu-cloud/cluster/mount-persistent-storage-to-workload.md).

4. When you no longer need the storage resources, [clean up persistent storage resources](https://docs.scitix.ai/gpu-cloud/cluster/cleanup-persistent-storage-resources.md).


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