CCE works with EVS to support snapshots. A snapshot is a complete copy or image of EVS disk data at a certain point of time, which can be used for data DR.
You can create snapshots to rapidly save the disk data at a certain point of time. In addition, you can use snapshots to create disks so that the created disks will contain the snapshot data in the beginning.
Precautions
- The snapshot function is available only for clusters of v1.15 or later and requires the CSI-based Everest add-on.
- The subtype (common I/O, high I/O, or ultra-high I/O), disk mode (SCSI or VBD), data encryption, sharing status, and capacity of an EVS disk created from a snapshot must be the same as those of the disk associated with the snapshot. These attributes cannot be modified after being queried or set.
- Snapshots can be created only for EVS disks that are available or in use, and a maximum of seven snapshots can be created for a single EVS disk.
- Snapshots can be created only for PVCs created using the storage class (whose name starts with csi) provided by the Everest add-on. Snapshots cannot be created for PVCs created using the Flexvolume storage class whose name is ssd, sas, or sata.
- Snapshot data of encrypted disks is stored encrypted, and that of non-encrypted disks is stored non-encrypted.
- A PVC of the xfs file system type can generate snapshots. The file system of the disk associated with the PVC created using these snapshots remains xfs.
Application Scenarios
The snapshot feature helps address your following needs:
- Routine data backup
You can create snapshots for EVS disks regularly and use snapshots to recover your data in case that data loss or data inconsistency occurred due to misoperations, viruses, or attacks.
- Rapid data restoration
You can create a snapshot or multiple snapshots before an OS change, application software upgrade, or a service data migration. If an exception occurs during the upgrade or migration, service data can be rapidly restored to the time point when the snapshot was created.
For example, a fault occurred on system disk A of ECS A, and therefore ECS A cannot be started. Because system disk A is already faulty, the data on system disk A cannot be restored by rolling back snapshots. In this case, you can use an existing snapshot of system disk A to create EVS disk B and attach it to ECS B that is running properly. Then, ECS B can read data from system disk A using EVS disk B.
The snapshot capability provided by CCE is the same as the CSI snapshot function provided by the Kubernetes community. EVS disks can be created only based on snapshots, and snapshots cannot be rolled back to source EVS disks.
- Rapid deployment of multiple services
You can use a snapshot to create multiple EVS disks containing the same initial data, and these disks can be used as data resources for various services, for example, data mining, report query, and development and testing. This method protects the initial data and creates disks rapidly, meeting the diversified service data requirements.
Creating a Snapshot
Using the CCE console
- Log in to the CCE console.
- Click the cluster name to go to the cluster console. Choose Storage in the navigation pane and click the Snapshots and Backups tab.
- Click Create Snapshot in the upper right corner. In the dialog box displayed, set related parameters.
- Snapshot Name: Enter a snapshot name.
- Storage: Select an EVS PVC.
- Click Create.
Using YAML
kind: VolumeSnapshot
apiVersion: snapshot.storage.k8s.io/v1beta1
metadata:
finalizers:
- snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
- snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
name: cce-disksnap-test # Snapshot name
namespace: default
spec:
source:
persistentVolumeClaimName: pvc-evs-test # PVC name. Only an EVS PVC can be selected.
volumeSnapshotClassName: csi-disk-snapclass
Using a Snapshot to Create a PVC
The disk type, encryption setting, and disk mode of the created EVS PVC are consistent with those of the snapshot's source EVS disk.
Using the CCE console
- Log in to the CCE console.
- Click the cluster name to go to the cluster console. Choose Storage in the navigation pane and click the Snapshots and Backups tab.
- Locate the snapshot that you want to use for creating a PVC, click Create PVC, and configure PVC parameters in the displayed dialog box.
- PVC Name: Enter a PVC name.
- Resource Tag: Resource tags can be added to classify resources, which is supported only when the Everest version in the cluster is 2.1.39 or later.
You can create predefined tags on the TMS console. The predefined tags are available to all resources that support tags. You can use predefined tags to improve the tag creation and resource migration efficiency.
CCE automatically creates system tags CCE-Cluster-ID={Cluster ID}, CCE-Cluster-Name={Cluster name}, and CCE-Namespace={Namespace name}. These tags cannot be modified.
- Click Create.
Using YAML
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: pvc-test
namespace: default
annotations:
everest.io/disk-volume-type: SSD # EVS disk type, which must be the same as that of the snapshot's source EVS disk.
everest.io/disk-volume-tags: '{"key1":"value1","key2":"value2"}' # (Optional) Custom resource tags
csi.storage.k8s.io/fstype: xfs # (Optional) Configure this field when the snapshot file system type is xfs.
labels:
failure-domain.beta.kubernetes.io/region: <your_region> # Replace the region with the one where the EVS disk is located.
failure-domain.beta.kubernetes.io/zone: <your_zone> # Replace the AZ with the one where the EVS disk is located.
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: csi-disk
dataSource:
name: cce-disksnap-test # Snapshot name
kind: VolumeSnapshot
apiGroup: snapshot.storage.k8s.io