Dynamic Provisioning of PVCs


This document describes how to dynamically provision a volume using Kubernetes and Portworx.

Using Dynamic Provisioning

Using Dynamic Provisioning and Storage Classes you don’t need to create Portworx volumes out of band and they will be created automatically. Using Storage Classes objects an admin can define the different classes of Portworx Volumes that are offered in a cluster. Following are the different parameters that can be used to define a Portworx Storage Class

Name Description Example
fs Filesystem to be laid out: xfs|ext4 fs: “ext4”
block_size Block size block_size: “32k”
repl Replication factor for the volume: 1|2|3 repl: “3”
shared Flag to create a globally shared namespace volume which can be used by multiple pods shared: “true”
priority_io IO Priority: low|medium|high priority_io: “high”
io_profile Overrides the I/O algorithm Portworx uses for a volume. The following values are supported: io_profile: “db”
group The group a volume should belong too. Portworx will restrict replication sets of volumes of the same group on different nodes. If the force group option ‘fg’ is set to true, the volume group rule will be strictly enforced. By default, it’s not strictly enforced. group: “volgroup1”
fg This option enforces volume group policy. If a volume belonging to a group cannot find nodes for it’s replication sets which don’t have other volumes of same group, the volume creation will fail. fg: “true”
label List of comma-separated name=value pairs to apply to the Portworx volume label: “name=mypxvol”
nodes Comma-separated Portworx Node ID’s to use for replication sets of the volume nodes: “minion1,minion2”
aggregation_level Specifies the number of replication sets the volume can be aggregated from aggregation_level: “2”
snap_schedule Snapshot schedule (PX 1.3 and higher). Following are the accepted formats:

periodic=mins,snaps-to-keep
daily=hh:mm,snaps-to-keep
weekly=weekday@hh:mm,snaps-to-keep
monthly=day@hh:mm,snaps-to-keep

snaps-to-keep is optional. Periodic, Daily, Weekly and Monthly keep last 5, 7, 5 and 12 snapshots by default respectively.
snap_schedule: periodic=60,10

snap_schedule: daily=12:00,4

snap_schedule: weekly=sunday@12:00,2

snap_schedule: monthly=15@12:00
snap_interval Snapshot interval in minutes. 0 disables snaps. Minimum value: 60. It is recommended to use snap_schedule above. snap_interval: “120”
sticky Flag to create sticky volumes that cannot be deleted until the flag is disabled sticky: “true”
journal (PX 1.3 and higher) Flag to indicate if you want to use journal device for the volume’s data. This will use the journal device that you used when installing Portworx. This is useful to absorb frequent syncs from short bursty workloads. Default: false journal: “true”

Provision volumes

Step 1: Create Storage Class.

Create the storageclass:

kubectl create -f examples/volumes/portworx/portworx-sc.yaml

Example:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: portworx-sc
provisioner: kubernetes.io/portworx-volume
parameters:
  repl: "1"

Download example

Verifying storage class is created:

kubectl describe storageclass portworx-sc
     Name: 	        	portworx-sc
     IsDefaultClass:	        No
     Annotations:		<none>
     Provisioner:		kubernetes.io/portworx-volume
     Parameters:		repl=1
     No events.

Step 2: Create Persistent Volume Claim.

Creating the persistent volume claim:

kubectl create -f examples/volumes/portworx/portworx-volume-pvcsc.yaml

Example:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvcsc001
  annotations:
    volume.beta.kubernetes.io/storage-class: portworx-sc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi

Download example

Verifying persistent volume claim is created:

kubectl describe pvc pvcsc001
Name:	      	pvcsc001
Namespace:      default
StorageClass:   portworx-sc
Status:	      	Bound
Volume:         pvc-e5578707-c626-11e6-baf6-08002729a32b
Labels:	      	<none>
Capacity:	    2Gi
Access Modes:   RWO
No Events.

Persistent Volume is automatically created and is bounded to this pvc.

Verifying persistent volume claim is created:

kubectl describe pv pvc-e5578707-c626-11e6-baf6-08002729a32b
Name: 	      	pvc-e5578707-c626-11e6-baf6-08002729a32b
Labels:        	<none>
StorageClass:  	portworx-sc
Status:	      	Bound
Claim:	      	default/pvcsc001
Reclaim Policy: 	Delete
Access Modes:   	RWO
Capacity:	        2Gi
Message:
Source:
Type:	      	PortworxVolume (a Portworx Persistent Volume resource)
VolumeID:   	374093969022973811
No events.

Step 3: Create Pod which uses Persistent Volume Claim with storage class.

Create the pod:

kubectl create -f examples/volumes/portworx/portworx-volume-pvcscpod.yaml

Example:

apiVersion: v1
kind: Pod
metadata:
  name: pvpod
spec:
  containers:
  - name: test-container
    image: gcr.io/google_containers/test-webserver
    volumeMounts:
    - name: test-volume
      mountPath: /test-portworx-volume
  volumes:
  - name: test-volume
    persistentVolumeClaim:
      claimName: pvcsc001

Download example

Verifying pod is created:

kubectl get pod pvpod
NAME      READY     STATUS    RESTARTS   AGE
pvpod       1/1     Running   0          48m
To access PV/PVCs with a non-root user refer here

Delete volumes

For dynamically provisioned volumes using StorageClass and PVC (PersistenVolumeClaim), if a PVC is deleted, the corresponding Portworx volume will also get deleted. This is because Kubernetes, for PVC, creates volumes with a reclaim policy of deletion. So the volumes get deleted on PVC deletion.

To delete the PVC and the volume, you can run kubectl delete -f <pvc_spec_file.yaml>



Last edited: Wednesday, Dec 4, 2019