Can a PVC be bound to a specific PV?

Question

This was discussed by k8s maintainers in https://github.com/kubernetes/kubernetes/issues/7438#issuecomment-97148195:

Allowing users to ask for a specific PV breaks the separation between them

I don't buy that. We allow users to choose a node. It's not the common case, but it exists for a reason.

How did it end? What's the intended way to have >1 PV's and PVC's like the one in https://github.com/kubernetes/kubernetes/tree/master/examples/nfs?

We use NFS, and PersistentVolume is a handy abstraction because we can keep the server IP and the path there. But a PersistentVolumeClaim gets any PV with sufficient size, preventing path reuse.

Can set volumeName in a PVC spec block (see https://github.com/kubernetes/kubernetes/pull/7529) but it makes no difference.

Answer 1

There is a way to pre-bind PVs to PVCs today, here is an example showing how:

1. Create a PV object with a ClaimRef field referencing a PVC that you will subsequently create:

    $ kubectl create -f pv.yaml  persistentvolume "pv0003" created 

   where pv.yaml contains:

    apiVersion: v1  kind: PersistentVolume  metadata:    name: pv0003  spec:    storageClassName: ""    capacity:      storage: 5Gi    accessModes:      - ReadWriteOnce    persistentVolumeReclaimPolicy: Retain    claimRef:      namespace: default      name: myclaim    nfs:      path: /tmp      server: 172.17.0.2 

2. Then create the PVC with the same name:

    kind: PersistentVolumeClaim  apiVersion: v1  metadata:    name: myclaim  spec:    storageClassName: ""    accessModes:      - ReadWriteOnce    resources:      requests:        storage: 5Gi 

3. The PV and PVC should be bound immediately:

    $ kubectl get pvc  NAME      STATUS    VOLUME    CAPACITY   ACCESSMODES   AGE  myclaim   Bound     pv0003    5Gi        RWO           4s  $ ./cluster/kubectl.sh get pv  NAME      CAPACITY   ACCESSMODES   STATUS    CLAIM             REASON    AGE  pv0003    5Gi        RWO           Bound     default/myclaim             57s 

Answer 2

It can be done using the keyword volumeName:

for example

apiVersion: "v1" kind: "PersistentVolumeClaim" metadata:   name: "claimapp80" spec:   accessModes:     - "ReadWriteOnce"   resources:     requests:       storage: "10Gi"   volumeName: "app080" 

will claim specific PV app080