Kubernetes Persistent Volumes (PV)

TOMERGE: Kubernetes Persistent volumes

Kubernetes Persistent Volumes subsystem provides an API for users and administrators that abstracts details of how storage is provided from how it is consumed

• https://kubernetes.io/docs/concepts/storage/persistent-volumes/
• https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.29/#persistentvolume-v1-core

• kubectl get pvc
• kubectl describe pvc mysql-pv-claim

Volumes:
VolumeMounts:
ExtraVolumes

Examples

 volumes:
 your-vol-1:
   Type:      ConfigMap (a volume populated by a ConfigMap)
   Name:      prod-admin-config
   Optional:  false

 your-vol-2:
   Type:        Secret (a volume populated by a Secret)
   SecretName:  your-secret-name
   Optional:    false

 your-vol-3:
   Type:                    Projected (a volume that contains injected data from multiple sources)
   TokenExpirationSeconds:  3607
   ConfigMapName:          your-kube-root-ca.crt
   ConfigMapOptional:       <nil>
   DownwardAPI:             true

• Claims: https://kubernetes.io/docs/concepts/storage/persistent-volumes/#claims-as-volumes

apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:
    - name: myfrontend
      image: nginx
      volumeMounts:
      - mountPath: "/var/www/html"
        name: mypd
  volumes:
    - name: mypd
      persistentVolumeClaim:
        claimName: myclaim

spec:
  volumes:
    - name: elasticsearch-master
      persistentVolumeClaim:
        claimName: elasticsearch-master-elasticsearch-master-0
    - name: mynewvolumen
      emptyDir: {}

Error

error: error validating "yourpv": error validating data: 
ValidationError(PersistentVolume.spec.csi): missing required field "volumeHandle" in 
io.k8s.api.core.v1.CSIPersistentVolumeSource; if you choose to ignore these errors, turn 
validation off with --validate=false

Metrics

kubelet_volume_stats_available_bytes
kubelet_volume_stats_capacity_bytes
kubelet_volume_stats_inodes
kubelet_volume_stats_inodes_free
kubelet_volume_stats_inodes_used
kubelet_volume_stats_used_bytes

Ref: https://stackoverflow.com/questions/44718268/how-to-monitor-disk-usage-of-kubernetes-persistent-volumes

News

• Jun 2018 v1.11 Resizing Persistent Volumes using Kubernetes in alpha

CKA

• CKA v1.23: Understand storage classes, persistent volumes
• CKA v1.18: Understand persistent volumes and know how to create them
• CKA v1.15: Understand PersistentVolumeClaims for storage

Activities

• Kubernetes: Rename PVs
• Access a volume with a temporary pod

Related terms

• Persistent Volume Claim (PVC)
• Volumes (Kubernetes)
• kubectl apply
• Container Storage Interface (CSI)
• defaultMode:
• values.yml
• kubernetes_persistent_volume
• kind: ConfigMap
• kind: PersistentVolume
• Terraform kubernetes resource: kubernetes persistent volume v1

See also

• Kubernetes volumes: volumeMounts:, mountPath, snapshots, spec.volumes
• Kubernetes storage, storage classes, PersistentVolume (PV), PVC, CSI, kind: StorageClass, kind: PersistentVolumeClaim, kind: PersistentVolume, kubectl [ get | describe | edit ] pvc, volumeClaimTemplates:, kubectl patch pv, FailedMount, Volume Expansion, Volume Cloning, snapshots, ExtraVolumes, NotTriggerScaleUp, volumePVCDataSource, AllowVolumeExpansion, EKS storage, provisioner, Storage Capacity Tracking, VolumeBinding, VolumeClaimTemplate, storage.k8s.io, CKA Storage, DoKC, EmptyDir, Volume populators