07.Storage - Storage Class

LABS – CERTIFIED KUBERNETES ADMINISTRATOR WITH PRACTICE TESTS > STORAGE

 

Storage

01. Persistent Volume Claims
02. Storage

 

01. How many StorageClasses exist in the cluster right now?

 

ask : 1

controlplane ~ ➜  k get StorageClass
NAME                   PROVISIONER             RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-path (default)   rancher.io/local-path   Delete          WaitForFirstConsumer   false                  5m15s

 

02. How about now? How many Storage Classes exist in the cluster?

 

We just created a few new Storage Classes. Inspect them.

 

controlplane ~ ➜  k get StorageClass
NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local-path (default)        rancher.io/local-path           Delete          WaitForFirstConsumer   false                  6m10s
local-storage               kubernetes.io/no-provisioner    Delete          WaitForFirstConsumer   false                  33s
portworx-io-priority-high   kubernetes.io/portworx-volume   Delete          Immediate              false                  33s

 

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

1) portWorx-Storageclass

2) glusterfs-sc

3) nfs-sc

4) local-storage

 

Hint : Look for the storage class name that uses no-provisioner

 

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

1) Immediate

 

2) WaitForFirstConsumer

 

Run the command: kubectl describe sc local-storage or kubectl get sc 
and look under the Volume Binding Mode section.

controlplane ~ ➜  k describe sc local-storage
Name:            local-storage
IsDefaultClass:  No
Annotations:     kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"storage.k8s.io/v1","kind":"StorageClass","metadata":{"annotations":{},"name":"local-storage"},"provisioner":"kubernetes.io/no-provisioner","volumeBindingMode":"WaitForFirstConsumer"}

Provisioner:           kubernetes.io/no-provisioner
Parameters:            <none>
AllowVolumeExpansion:  <unset>
MountOptions:          <none>
ReclaimPolicy:         Delete
VolumeBindingMode:     WaitForFirstConsumer
Events:                <none>

 

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

portworx-io-priority-high라는 스토리지 클래스에 사용되는 프로비저닝 도구는 무엇입니까?

 

1) no-provisioner

2) local-volume

3) portworx-volume

4) ceph-volue

 

Run the command: kubectl describe sc portworx-io-priority-high 
or 
kubectl get sc portworx-io-priority-high
 and look under the PROVISIONER section.

controlplane ~ ➜  kubectl describe sc portworx-io-priority-high
Name:            portworx-io-priority-high
IsDefaultClass:  No
Annotations:     kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"storage.k8s.io/v1","kind":"StorageClass","metadata":{"annotations":{},"name":"portworx-io-priority-high"},"parameters":{"priority_io":"high","repl":"1","snap_interval":"70"},"provisioner":"kubernetes.io/portworx-volume"}

Provisioner:           kubernetes.io/portworx-volume
Parameters:            priority_io=high,repl=1,snap_interval=70
AllowVolumeExpansion:  <unset>
MountOptions:          <none>
ReclaimPolicy:         Delete
VolumeBindingMode:     Immediate
Events:                <none>

 

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

 

ask : NO

 

controlplane ~ ➜  k get pv
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS    REASON   AGE
local-pv   500Mi      RWO            Retain           Available           local-storage            6m57s

controlplane ~ ➜  k get pvc
No resources found in default namespace.

 

07. Let's fix that. Create 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
• Correct Access Mode?
• Correct StorageClass Used?
• PVC requests volume size = 500Mi?

Inspect the persistent volume and look for the Access Mode,
Storage and StorageClassName used. Use this information to create the PVC.

 

# local-pv yaml
--
apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 500Mi
  local:
    path: /opt/vol1
  persistentVolumeReclaimPolicy: Retain
  storageClassName: local-storage
  volumeMode: Filesystem

Use the below YAML file to create the PersistentVolumeClaim local-pvc:

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

 

08. What is the status of the newly created Persistent Volume Claim?

ask : Pending

 

controlplane ~ ➜  k get pvc,pv
NAME                              STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS    AGE
persistentvolumeclaim/local-pvc   Pending                                      local-storage   49s

NAME                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS    REASON   AGE
persistentvolume/local-pv   500Mi      RWO            Retain           Available           local-storage            14m

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

local-pv라는 볼륨을 요청하기 위해 유효한 요청을 했음에도 불구하고 PVC가 보류 상태인 이유는 무엇입니까?

Inspect the PVC events.

1) Persistent Volume and Claim mismatch

2) PVC Specs are Incorrect

3) Storage Class not found

4) A Pod consuming the volume is not scheduled

볼륨을 사용하는 Pod가 예약되지 않았습니다.

10. The Storage Class called local-storage makes use of VolumeBindingMode set to WaitForFirstConsumer.

local-storage라는 스토리지 클래스는 WaitForFirstConsumer로 설정된 VolumeBindingMode를 사용합니다.

 

This will delay the binding and provisioning of a PersistentVolume until a Pod using the PersistentVolumeClaim is created.

 

local-storage라고 하는 스토리지 클래스는 VolumeBindingModeThis를 사용하여 PersistentVolumeClaim을 사용하는 파드가 생성될 때까지 PersistentVolume의 바인딩 및 프로비저닝을 지연시킵니다. WaitForFirstConsumer로 설정합니다.

11. 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?

Use the command 

kubectl run to create a pod definition file for nginx pod with image nginx:alpine.

Add mount volume path /var/www/html and pvc given in the details.

Alternatively, run the command:

kubectl run nginx --image=nginx:alpine --dry-run=client -oyaml > nginx.yaml​

Solution manifest file to create a pod called nginx is as follows:

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

 

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

1) AVAILABLE

2) ERROR

3) BOUND

4) PENDING

5) TERMINATING

controlplane ~ ✖ k get pv,pvc
NAME                        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS    REASON   AGE
persistentvolume/local-pv   500Mi      RWO            Retain           Bound    default/local-pvc   local-storage            27m

NAME                              STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS    AGE
persistentvolumeclaim/local-pvc   Bound    local-pv   500Mi      RWO            local-storage   13m

 

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

아래 사양을 사용하는 delay-volume-sc라는 새 스토리지 클래스를 만듭니다.

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

 

• Storage Class uses: kubernetes.io/no-provisioner ?
• Storage Class volumeBindingMode set to WaitForFirstConsumer ?

 

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

---

Bookmark

 

https://kubernetes.io/ko/docs/concepts/storage/storage-classes/

스토리지 클래스

https://kubernetes.io/docs/concepts/storage/persistent-volumes/

Persistent Volumes

https://kubernetes.io/ko/docs/tasks/configure-pod-container/configure-persistent-volume-storage/

스토리지로 퍼시스턴트볼륨(PersistentVolume)을 사용하도록 파드 설정하기