// Module included in the following assemblies:
//
// * storage/container_storage_interface/persistent-storage-csi-group-snapshots.adoc

:_mod-docs-content-type: CONCEPT
[id="persistent-storage-csi-group-snapshots-overview_{context}"]
= Overview of CSI volume group snapshots

[role="_abstract"]
Volume group snapshots capture point-in-time copies of multiple persistent volume claims using label selectors. Three API objects manage snapshots: VolumeGroupSnapshot, VolumeGroupSnapshotContent, and VolumeGroupSnapshotClass. 

:FeatureName: CSI volume group snapshots
include::snippets/technology-preview.adoc[leveloffset=+1]

To use this Technology Preview feature, you must enable it by using feature gates. For information about using feature gates, see "Enabling features using feature gates". 

Snapshot:: A snapshot represents the state of the storage volume in a cluster at a particular point in time. Volume snapshots can be used to provision a new volume. 

Volume group snapshot:: A volume group snapshot uses a label selector to group multiple persistent volume claims for snapshotting. A volume group snapshot represents copies from multiple volumes that are taken at the same point-in-time. This can be useful for applications that contain multiple volumes.

To use volume group snapshots, familiarity with persistent volumes is suggested. For information about persistent volumes, see "Understanding persistent volumes".

Volume group snapshots provide three new API objects for managing snapshots:

`VolumeGroupSnapshot`::
Requests creation of a volume group snapshot for multiple persistent volume claims. It contains information about the volume group snapshot operation, such as the timestamp when the volume group snapshot was taken, and whether it is ready to use. 

`VolumeGroupSnapshotContent`::
Created by the snapshot controller for a dynamically created volumeGroupSnapshot. It contains information about the volume group snapshot including the volume group snapshot ID. This object represents a provisioned resource on the cluster (a group snapshot). The `VolumeGroupSnapshotContent` object binds to the volume group snapshot for which it was created with a one-to-one mapping.

`VolumeGroupSnapshotClass`::
Created by cluster administrators to describe how volume group snapshots should be created, including the driver information, the deletion policy, etc.

These three API kinds are defined as `CustomResourceDefinitions` (CRDs). These CRDs must be installed in a {product-title} cluster for a CSI driver to support volume group snapshots.