Kubernetes Storage Operations: Difference between revisions

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Line 83: Line 83:
spec:
spec:
   accessModes:
   accessModes:
   - RedWriteOnce
   - ReadWriteOnce
   storageClassName: manual-local-storage
   storageClassName: manual-local-storage
   resources:
   resources:
     requests:
     requests:
       storage: 10 Gi
       storage: 10Gi
</syntaxhighlight>
</syntaxhighlight>


Aside from attributes like storage amount request access mode, the storage class name must match.
Aside from attributes like storage amount request access mode, the storage class name must match.

Revision as of 02:51, 12 December 2019

Internal

Get Information about Persistent Volumes

kubectl get pv <pv-name>
kubectl describe pv <pv-name>

Get Information about Persistent Volumes Claims

kubectl get pvc <pvc-name>
kubectl describe pvc <pvc-name>

Get Information about Storage Classes

NFS volume Example

This is an example to setup and use an nfs volume.

TODO: https://github.com/kubernetes/examples/tree/master/staging/volumes/nfs

Local Volumes

Create a Local Volume, the corresponding Persistent Volume and a Persistent Volume Claim that Binds to It

This is the step-by-step procedure to create a persistent volume backed by a local volume and expose it to a pod with a matching persistent volume claim.

Expose a Local Disk

In this context, "exposing a local disk" means exposing a raw block device. TODO.

Expose a Local Directory

Define a local directory that will be exposed as a persistent volume:

mkdir /mnt/disk1/local-volume-0

Define the persistent volume API resource instance:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: worker-00-local-volume-0
spec:
  capacity:
    storage: 10Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: manual-local-storage
  local:
    path: /mnt/disk1/local-volume-0
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - worker-00

Note that in the persistent volume metadata shown above, "worker-00" is the name of the node, as known to Kubernetes. It can be obtained with:

kubectl get nodes -o wide

If the cluster has more than one node, symmetrical persistent volumes can be created for other nodes as well.

Upon creation, the persistent volumes can be listed with:

kubectl get pv
NAME                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS           REASON   AGE
worker-00-local-volume-0   10Gi       RWO            Delete           Available           manual-local-storage            94s
worker-01-local-volume-0   10Gi       RWO            Delete           Available           manual-local-storage            2s

Create a Matching Persistent Volume Claim

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: local-storage-claim
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: manual-local-storage
  resources:
    requests:
      storage: 10Gi

Aside from attributes like storage amount request access mode, the storage class name must match.