K
Q

Kubernetes Unable to mount volumes for pod

5/7/2018

I'm trying to setup a volume to use with Mongo on k8s.

I use kubectl create -f pv.yaml to create the volume.

pv.yaml:

kind: PersistentVolume
apiVersion: v1
metadata:
  name: pvvolume
  labels:
    type: local
spec:
  storageClassName: standard
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/nfs"
  claimRef:
    kind: PersistentVolumeClaim
    namespace: default
    name: pvvolume

I then deploy this StatefulSet that has pods making PVCs to this volume.

My volume seems to have been created without problem, I'm expecting it to just use the storage of the host node.

When I try to deploy I get the following error:

Unable to mount volumes for pod "mongo-0_default(2735bc71-5201-11e8-804f-02dffec55fd2)": timeout expired waiting for volumes to attach/mount for pod "default"/"mongo-0". list of unattached/unmounted volumes=[mongo-persistent-storage]

Have a missed a step in setting up my persistent volume?

-- Philip Kirkbride
kubernetes
kubernetes-pvc

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2 Answers

5/4/2020

My case is an edge case, and I doubt that you will reach it. However, I will describe it because, it cost me a lot of grey hairs - and maybe it will save yours.

This same error occurred for me despite PV and PVC being binned. Pod was constantly in ContainerCreating stare, yet kubectl get events throw the error asked in this question.

$ kubectl get pv
NAME        CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                     STORAGECLASS   REASON   AGE
sewage-db   5Ti        RWO            Retain           Bound    global-sewage/sewage-db   nfs                     3h40m

$kubectl get pvc -n global-sewage 
NAME        STATUS   VOLUME      CAPACITY   ACCESS MODES   STORAGECLASS   AGE
sewage-db   Bound    sewage-db   5Ti        RWO            nfs            3h39m

After rebooting the server it turned out that, one of 32GiB RAM physical memory was corrupted. Removing the memory fixed the issue.

-- Lukasz Dynowski
Source: StackOverflow
5/7/2018

A persistent volume is just the declaration of availability of some storage inside your kubernetes cluster. There is no binding with your pod at this stage.

Since your pod is deployed through a StatefulSet, there should be in your cluster one or more PersistentVolumeClaims which are the objects that connect a pod with a PersistentVolume.

In order to manually bind a PV with a PVC you need to edit your PVC by adding the following in its spec section:

volumeName: "<your persistent volume name>"

Here an explanation on how this process works: https://docs.openshift.org/latest/dev_guide/persistent_volumes.html#persistent-volumes-volumes-and-claim-prebinding

-- whites11
Source: StackOverflow