Mayastor User Reference
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Volume Snapshots

Volume snapshots are copies of a persistent volume at a specific point in time. They can be used to restore a volume to a previous state or create a new volume. Mayastor provides support for industry standard copy-on-write (COW) snapshots, which is a popular methodology for taking snapshots by keeping track of only those blocks that have changed. Mayastor incremental snapshot capability enhances data migration and portability in Kubernetes clusters across different cloud providers or data centers. Using standard kubectl commands, you can seamlessly perform operations on snapshots and clones in a fully Kubernetes-native manner.
Use cases for volume snapshots include:
  • Efficient replication for backups.
  • Utilization of clones for troubleshooting.
  • Development against a read-only copy of data.
Volume snapshots allow the creation of read-only incremental copies of volumes, enabling you to maintain a history of your data. These volume snapshots possess the following characteristics:
  • Consistency: The data stored within a snapshot remains consistent across all replicas of the volume, whether local or remote.
  • Immutability: Once a snapshot is successfully created, the data contained within it cannot be modified.
Currently, Mayastor supports the following operations related to volume snapshots:
  1. 1.
    Creating a snapshot for a PVC
  2. 2.
    Listing available snapshots for a PVC
  3. 3.
    Deleting a snapshot for a PVC

Prerequisites

  1. 1.
    Deploy and configure Mayastor by following the steps given here and create disk pools.
  2. 2.
    Create a Mayastor StorageClass with single replica.
Currently, Mayastor only supports snapshots for volumes with a single replica. Snapshot support for volumes with more than one replica will be available in the future versions.
Command (single replica)
YAML (single replica)
cat <<EOF | kubectl create -f -
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: mayastor-1
parameters:
ioTimeout: "30"
protocol: nvmf
repl: "1"
provisioner: io.openebs.csi-mayastor
EOF
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
name: mayastor-1
parameters:
ioTimeout: "30"
protocol: nvmf
repl: "1"
provisioner: io.openebs.csi-mayastor
  1. 3.
    Create a PVC using these steps and check if the status of the PVC is Bound.
Command
Example Output
kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
ms-volume-claim Bound pvc-fe1a5a16-ef70-4775-9eac-2f9c67b3cd5b 1Gi RWO mayastor-1 15s
Copy the PVC name, for example, ms-volume-claim.
  1. 4.
    (Optional) Create an application by following these steps.

Create a Snapshot

You can create a snapshot (with or without an application) using the PVC. Follow the steps below to create a volume snapshot:

Step 1: Create a Kubernetes VolumeSnapshotClass object

Command
YAML
cat <<EOF | kubectl create -f -
kind: VolumeSnapshotClass
apiVersion: snapshot.storage.k8s.io/v1
metadata:
name: csi-mayastor-snapshotclass
annotations:
snapshot.storage.kubernetes.io/is-default-class: "true"
driver: io.openebs.csi-mayastor
deletionPolicy: Delete
EOF
kind: VolumeSnapshotClass
apiVersion: snapshot.storage.k8s.io/v1
metadata:
name: csi-mayastor-snapshotclass
annotations:
snapshot.storage.kubernetes.io/is-default-class: "true"
driver: io.openebs.csi-mayastor
deletionPolicy: Delete
Parameters
Type
Description
Name
String
Custom name of the snapshot class
Driver
String
CSI provisioner of the storage provider being requested to create a snapshot (io.openebs.csi-mayastor)
Apply VolumeSnapshotClass details
Command
Example Output
kubectl apply -f class.yaml
volumesnapshotclass.snapshot.storage.k8s.io/csi-mayastor-snapshotclass created

Step 2: Create the snapshot

Command
YAML
cat <<EOF | kubectl create -f -
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
name: mayastor-pvc-snap-1
spec:
volumeSnapshotClassName: csi-mayastor-snapshotclass
source:
persistentVolumeClaimName: ms-volume-claim
EOF
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
name: mayastor-pvc-snap-1
spec:
volumeSnapshotClassName: csi-mayastor-snapshotclass
source:
persistentVolumeClaimName: ms-volume-claim
Parameters
Type
Description
Name
String
Name of the snapshot
VolumeSnapshotClassName
String
Name of the created snapshot class
PersistentVolumeClaimName
String
Name of the PVC. Example- ms-volume-claim
Apply the snapshot
Command
Example Output
kubectl apply -f snapshot.yaml
volumesnapshot.snapshot.storage.k8s.io/mayastor-pvc-snap-1 created
When a snapshot is created on a thick-provisioned volume, the storage system automatically converts it into a thin-provisioned volume.

List Snapshots

To retrieve the details of the created snapshots, use the following command:
Command
Example Output
kubectl get volumesnapshot
NAME READYTOUSE SOURCEPVC SOURCESNAPSHOTCONTENT RESTORESIZE SNAPSHOTCLASS SNAPSHOTCONTENT CREATIONTIME AGE
mayastor-pvc-snap-1 true ms-volume-claim 1Gi csi-mayastor-snapshotclass snapcontent-174d9cd9-dfb2-4e53-9b56-0f3f783518df 57s 57s
Command
Example Output
kubectl get volumesnapshotcontent
NAME READYTOUSE RESTORESIZE DELETIONPOLICY DRIVER VOLUMESNAPSHOTCLASS VOLUMESNAPSHOT VOLUMESNAPSHOTNAMESPACE AGE
snapcontent-174d9cd9-dfb2-4e53-9b56-0f3f783518df true 1073741824 Delete io.openebs.csi-mayastor csi-mayastor-snapshotclass mayastor-pvc-snap-1 default 87s

Delete a Snapshot

To delete a snapshot, use the following command:
Command
Example Output
kubectl delete volumesnapshot mayastor-pvc-snap-1
volumesnapshot.snapshot.storage.k8s.io "mayastor-pvc-snap-1" deleted