Create a PVC from a snapshot in OCP on bare metal
This document will show you how to take a snapshot of a volume using Portworx and use that snapshot as the volume for a new pod.
The suggested way to manage snapshots on Kuberenetes is now to use Stork. Instructions for using Stork to manage snapshots can be found here
Managing snapshots through oc
Taking periodic snapshots on a running POD
When you create the Storage Class, you can specify a snapshot schedule on the volume as specified below:
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
name: portworx-io-priority-high
provisioner: pxd.portworx.com
parameters:
repl: "1"
snap_interval: "24"
io_priority: "high"
Creating a snapshot on demand
You can trigger a new snapshot on a running POD by creating a PersistentVolumeClaim.
Using annotations
Portworx uses a special annotation px/snapshot-source-pvc which can be used to identify the name of the source PVC whose snapshot needs to be taken.
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
namespace: prod
name: ns.prod-name.px-snap-1
annotations:
volume.beta.kubernetes.io/storage-class: px-sc
px/snapshot-source-pvc: px-vol-1
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 6Gi
Note the format of the name field - ns.<namespace_of_source_pvc>-name.<name_of_the_snapshot>. The above example takes a snapshot with the name px-snap-1 of the source PVC px-vol-1 in the prod namespace.
You can run the following command to edit your existing Portworx ClusterRole
oc edit clusterrole node-get-put-list-role
Clone from a snapshot
You can restore a clone from a snapshot using the following spec file. In 1.3 and higher releases, this is required to create a read-write clone as snapshots are read only.
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
namespace: prod
name: ns.prod-name.px-snap-restore
annotations:
volume.beta.kubernetes.io/storage-class: px-sc
px/snapshot-source-pvc: ns.prod-name.px-snap-1
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 2Gi
The above example restores a volume from the source snapshot PVC with name ns.prod-name.px-snap-1.
Using inline spec
If you do not wish to use annotations you can take a snapshot by providing the source PVC name in the name field of the claim. However this method does not allow you to provide namespaces.
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: name.snap001-source.pvc001
annotations:
volume.beta.kubernetes.io/storage-class: px-sc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
Note the format of the “name” field. The format is name.<new_snap_name>-source.<old_volume_name>. Above example references the parent (source) persistent volume claim pvc001 and creates a snapshot by the name snap001.
Clone from a snapshot
You can restore a clone from a snapshot using the following spec file. In 1.3 and higher releases, this is required to create a read-write clone as snapshots are read only.
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: name.rollback001-source.snap001
annotations:
volume.beta.kubernetes.io/storage-class: px-sc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
Note we used used the existing snapshot name in the source part of the inline spec.
Using snapshots
Listing snapshots
To list your snapshots, use the pxctl volume list --snapshot command as follows:
pxctl volume list --snapshot
ID NAME SIZE HA SHARED IO_PRIORITY SCALE STATUS
1067822219288009613 snap001 1 GiB 2 no LOW 1 up - detached
You can use the ID or NAME of the snapshots when using them to restore a volume.
Restoring a pod from a snapshot
To restore a pod to use the created snapshot, use the pvc name.snap001-source.pvc001 in the pod spec.
Managing snapshots through pxctl
To demonstrate the capabilities of the SAN like functionality offered by Portworx, try creating a snapshot of your mysql volume.
First create a database and a demo table in your mysql container.
mysql --user=root --password=password
create database pxdemo;
Query OK, 1 row affected (0.00 sec)
use pxdemo;
Database changed
create table grapevine (counter int unsigned);
Query OK, 0 rows affected (0.04 sec)
quit;
Bye
Create a snapshot of this database using pxctl
First use pxctl volume list to see what volume you want to snapshot
bin/pxctl volume list
ID NAME SIZE HA SHARED ENCRYPTED IO_PRIORITY SCALE STATUS
381983511213673988 pvc-xxxxxxxx-xxxx-xxxx-xxxx-7cd30ac1a138 20 GiB 2 no no LOW 0 up - attached on xx.xx.105.241
Then use pxctl to snapshot your volume
pxctl volume snapshot 381983511213673988 --name snap-01
Volume successfully snapped: 835956864616765999
You can use pxctl to see your snapshot
pxctl snap list
ID NAME SIZE HA SHARED ENCRYPTED IO_PRIORITY SCALE STATUS
835956864616765999 snap-01 20 GiB 2 no no LOW 0 up - detached
Now you can create a mysql Pod to mount the snapshot
oc create -f portworx-mysql-snap-pod.yaml
apiVersion: v1
kind: Pod
metadata:
name: test-portworx-snapped-volume-pod
spec:
containers:
- image: mysql:5.6
name: mysql-snap
env:
# Use secret in real usage
- name: MYSQL_ROOT_PASSWORD
value: password
ports:
- containerPort: 3306
name: mysql
volumeMounts:
- name: snap-01
mountPath: /var/lib/mysql
volumes:
- name: snap-01
# This Portworx volume must already exist.
portworxVolume:
volumeID: "vol1"
Inspect that the database shows the cloned tables in the new mysql instance.
mysql --user=root --password=password
show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| pxdemo |
+--------------------+
4 rows in set (0.00 sec)
use pxdemo;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
show tables;
+------------------+
| Tables_in_pxdemo |
+------------------+
| grapevine |
+------------------+
1 row in set (0.00 sec)