ceph-csi/docs/static-pvc.md

Static PVC with ceph-csi

• Static PVC with ceph-csi
  • RBD static PVC
    • Create RBD image
    • Create RBD static PV
    • RBD Volume Attributes in PV
    • Create RBD static PVC

This document outlines how to create static PV and static PVC from existing rbd image

warning static PVC can be created, deleted, mounted and unmounted but currently ceph-csi doesn't support other operations like snapshot,clone, resize, etc for static PVC

RBD static PVC

RBD images created manually can be mounted and unmounted to an app, below step shows how to create a rbd image, static PV, static PVC

Create RBD image

If you already have a rbd image created and contains some data which you want to access by the application pod you can skip this step.

Lets create a new rbd image in ceph cluster which we are going to use for static PVC

[$]rbd create static-image --size=1024 --pool=replicapool

Create RBD static PV

To create the rbd PV you need to know the rbd image name,clusterID and pool name in which the rbd image is created

apiVersion: v1
kind: PersistentVolume
metadata:
  name: fs-static-pv
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 1Gi
  csi:
    driver: rbd.csi.ceph.com
    fsType: ext4
    nodeStageSecretRef:
      # node stage secret name
      name: csi-rbd-secret
      # node stage secret namespace where above secret is created
      namespace: default
    volumeAttributes:
      # Required options from storageclass parameters need to be added in volumeAttributes
      "clusterID": "ba68226a-672f-4ba5-97bc-22840318b2ec"
      "pool": "replicapool"
      "staticVolume": "true"
      #mounter: rbd-nbd
    # volumeHandle should be same as rbd image name
    volumeHandle: static-image
  persistentVolumeReclaimPolicy: Retain
  # The volumeMode can be either `Filesystem` or `Block` if you are creating Filesystem PVC it should be `Filesystem`, if you are creating Block PV you need to change it to `Block`
  volumeMode: Filesystem

RBD Volume Attributes in PV

Below table explains the list of volume attributes can be set when creating a static RBD PV

Attributes	Description	Required
clusterID	The is used by the CSI plugin to uniquely identify and use a Ceph cluster (this is the key in configmap created duing ceph-csi deployment)	Yes
pool	The pool name in which rbd image is created	Yes
staticVolume	Value must be set to true to mount and unmount static rbd PVC	yes
mounter	If set to rbd-nbd, use rbd-nbd on nodes that have rbd-nbd and nbd kernel modules to map rbd images	No

Note ceph-csi does not supports rbd image deletion for static PV. persistentVolumeReclaimPolicy in PV spec must be set to Retain to avoid PV delete attempt in csi-provisioner.

[$] kubectl create -f fs-static-pv.yaml
persistentvolume/fs-static-pv created

Create RBD static PVC

To create the rbd PVC you need to know the PV name which is created above

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: fs-static-pvc
  namespace: default
spec:
  accessModes:
  # ReadWriteMany is only supported for Block PVC
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  # The volumeMode can be either `Filesystem` or `Block` if you are creating Filesystem PVC it should be `Filesystem`, if you are creating Block PV you need to change it to `Block`
  volumeMode: Filesystem
  # volumeName should be same as PV name
  volumeName: fs-static-pv

[$] kubectl create -f fs-static-pvc.yaml
persistentvolumeclaim/fs-static-pvc created

Note deleting PV and PVC doesnot deleted the backend rbd image, user need to manually delete the rbd image if required