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 pv
• kubectl get pvc
• kubectl get pv,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

• Aug 2024 Persistent Volume last phase transition time
• 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, projected volumes, PVC
• 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, storageclass.kubernetes.io, Rook, Longhorn, projected volumes

https://kubernetes.io/blog/2024/08/13/kubernetes-v1-31-release/#persistent-volume-last-phase-transition-time