Let's say the following is being returned when attempting to start a pod.

FailedAttachVolume   pod/my-pod-4n89p    Multi-Attach error for volume "pvc-2db07c57-e282-48e7-bfb1-4cbd7245c25e" Volume is already used by pod(s) my-pod-k8vr2

The oc describe persistentvolume command can be used to determine the Access Mode of the Persistent Volume (RWO in this example)

~]$ oc describe persistentvolume pvc-2db07c57-e282-48e7-bfb1-4cbd7245c25e
Name:            pvc-2db07c57-e282-48e7-bfb1-4cbd7245c25e
Labels:          <none>
Annotations:     pv.kubernetes.io/provisioned-by: csi.trident.netapp.io
Finalizers:      [kubernetes.io/pv-protection external-attacher/csi-trident-netapp-io]
StorageClass:    file-storage
Status:          Bound
Claim:           my-namespace/my-persistent-volume-claim
Reclaim Policy:  Delete
Access Modes:    RWO
VolumeMode:      Filesystem
Capacity:        1Gi
Node Affinity:   <none>

Or, the oc get persistentvolume command can be used.

~]$ oc get persistentvolume pvc-2db07c57-e282-48e7-bfb1-4cbd7245c25e --output jsonpath={.spec.accessModes[*]}
ReadWriteOnce

Notice in this example that the Persistent Volume Access Mode is ReadWriteOnce (RWO). 

• ReadWriteOnce (RWO) - The volume may only be mounted on a single node
• ReadWriteOncePod (RWOP) - The volume may only be mounted on a single pod
• ReadOnlyMany (ROX) - The volume may be mounted on different nodes
• ReadWriteMany (RWX) - The volume can be mounted on different nodes

The oc get pods command with the --output wide option can be used to see that the pod that already has the Persistent Volume mounted (my-pod-k8vr2) is running on node worker-hsjrp, and the Persistent Volume could not be attached to my-pod-4n89p because the pod is running on a different node (worker-v8r9r).

~]# oc get pods -o wide --namespace project001
NAME            READY   STATUS               RESTARTS  AGE  IP              NODE          NOMINATED MODE
my-pod-k8vr2    1/1     Running              0         8d   10.142.118.51   worker-hsjrp  <none>
my-pod-4n89p    0/1     ContainerCreating    0         12m  <none>          worker-v8r9r  <none>