Practice Test: Storage Class

ㅁ How many StorageClasses exist in the cluster right now?

kubectl get storageclasses

ㅁ How about now? How many Storage Classes exist in the cluster? we just created a few new Storage Classes. Inspect them

$ kubectl get sc     
NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-storage               kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  10s
portworx-io-priority-high   kubernetes.io/portworx-volume   Delete          Immediate              false                  10s

 

ㅁ What is the name of the Storage Class that does not support dynamic volume provisioning?

[portWorx-Storageclass]

[glusterfs-sc]

[nfs-sc]

[local-storage]

 

ㅁ What is the Volume Binding Mode used for this storage class (the one identified in the previous question)

[WaiForFirstConsumer]

[Immediate]

 

ㅁ What is the Provisioner used for the storage class called portworx-io-priority-high?

[no-provisioner]

[ceph-volu]

[local-volume]

[portworx-volume]

 

ㅁ Is there a PersistentVolumeClaim that is consuming the PersistentVolume called local-pv?

$ kubectl get pvc

No resources found in default namespace.

[YES] [NO]

 

ㅁ Let's fix that. Creat a new PersistentVolumeClaim by the name of local-pvc that should bind to the volume local-pv. Inspect the pv local-pv for the specs.

- PVC: local-pvc

- Corrrect Access Mode?

- Correct StorageClass Used?

- PVC requests volume size = 500Mi?

 

$ kubectl describe pv local-pv

Name:              local-pv
Labels:            <none>
Annotations:       <none>
Finalizers:        [kubernetes.io/pv-protection]
StorageClass:      local-storage
Status:            Available
Claim:             
Reclaim Policy:    Retain
Access Modes:      RWO
VolumeMode:        Filesystem
Capacity:          500Mi
Node Affinity:     
  Required Terms:  
    Term 0:        kubernetes.io/hostname in [controlplane]
Message:           
Source:
    Type:  LocalVolume (a persistent volume backed by local storage on a node)
    Path:  /opt/vol1

 local-pvc.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: local-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 500Mi
  storageClassName: local-storage

 

ㅁ What is the status of the newly created Persistent Volume Claim?

$ kubectl get pvc

NAME        STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS    AGE
local-pvc   Pending                                      local-storage   8m43s

 

ㅁ Why is the PVC in a pending state despite making a valid request to claim the volume called local-pv?

[Storage class not found]

[PVC Specs are Incorrect]

[Persistent Volume and Claim mismatch]

[A Pod consuming the volume is not scheduled]

 

$ kubectl get sc     
NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-storage               kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  24m
portworx-io-priority-high   kubernetes.io/portworx-volume   Delete          Immediate              false                  24m

$ kubectl get pods

No resources found in default namespace.

 

Note: The Storage Class called local-storage makes use of VolumeBindingMode set to WaitForFirstConsumer. This will delay the binding and provisioning of a PersistentVolume until a Pod using the PersistentVolumeClaim is created

 

ㅁ Create a new pod called nginx with the image nginx:alpine. The Pod should make use of the PVC local-pvc and mount the volume at the path /var/www/html. 

The PV local-pv should in a bound state

 

- Pod created with the correct Image?

- Pod uses PVC called local-pvc?

- local-pv bound?

- nginx pod running?

- Volume mounted at the correct path?

 

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: nginx:alpine
    volumeMounts:
    - name: html-vol
      mountPath: /var/www/html
  volumes:
  - name: html-vol
    persistentVolumeClaim:
      claimName: local-pvc

$ kubectl get pvc

NAME        STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS    AGE
local-pvc   Bound    local-pv   500Mi      RWO            local-storage   21m

$ kubectl get pod

NAME    READY   STATUS    RESTARTS   AGE
nginx   1/1     Running   0          29s

$ kubectl get pv
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS    REASON   AGE
local-pv   500Mi      RWO            Retain           Bound    default/local-pvc   local-storage            34m

ㅁ What is the status of the local-pvc Persistent Volume Claim now?

[Bound]

 

ㅁ Create a new Storage Class called delayed-volume-sc that makes use of the below specs:

- provisioner: kubernetes.io/no-provisioner
- volumeBindingMode: WaitForFirstConsumer

 

sc-definition.yaml

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: delayed-volume-sc
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

$ kubectl get sc

NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
delayed-volume-sc           kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  47s
local-storage               kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  50m
portworx-io-priority-high   kubernetes.io/portworx-volume   Delete          Immediate              false                  50m