Kubernetes Container Orchestration Storage Solutions 5 — Questions and Answers
Question 1: What Kubernetes feature allows storage capacity information to be published so the scheduler can make volume-aware placement decisions?
- StorageClass topology keys
- CSIStorageCapacity objects (Correct answer)
- VolumeNodeAffinity hints
- PVCapacityMap
Correct answer: CSIStorageCapacity objects
CSIStorageCapacity objects, created by CSI drivers, expose available capacity per topology segment so the scheduler avoids placing pods where storage would be insufficient.
Question 2: Which kubectl command shows the events associated with a PersistentVolumeClaim to help diagnose binding issues?
- kubectl get pvc -o wide
- kubectl describe pvc <name> (Correct answer)
- kubectl logs pvc/<name>
- kubectl inspect pvc <name>
Correct answer: kubectl describe pvc <name>
kubectl describe pvc shows the full PVC spec, status, and the Events section which lists binding attempts, provisioner errors, and other diagnostic messages.
Question 3: What is the effect of setting 'ReadWriteOncePod' as the access mode for a PersistentVolumeClaim?
- The volume can be mounted by one pod at a time across the entire cluster (Correct answer)
- The volume can be mounted by multiple pods on a single node
- The volume is read-only for all pods except the owner pod
- The volume can be mounted by any pod in the same namespace
Correct answer: The volume can be mounted by one pod at a time across the entire cluster
ReadWriteOncePod (RWOP), introduced in Kubernetes 1.22, ensures the volume is mounted by exactly one pod across the whole cluster, stricter than ReadWriteOnce.
Question 4: In the context of Kubernetes storage, what does 'dynamic provisioning' mean?
- Volumes are pre-created by an administrator and listed in etcd
- A StorageClass provisioner automatically creates a PV when a matching PVC is submitted (Correct answer)
- Pods dynamically resize their volumes based on usage
- Volumes are provisioned at cluster bootstrap and assigned on demand
Correct answer: A StorageClass provisioner automatically creates a PV when a matching PVC is submitted
Dynamic provisioning means a provisioner plugin (in-tree or CSI) automatically creates a PersistentVolume to satisfy a PVC without manual administrator intervention.
Question 5: What must be true for a PersistentVolume to bind to a PersistentVolumeClaim?
- The PV must be in the same namespace as the PVC
- The PV capacity, access mode, and StorageClass must all satisfy the PVC's request (Correct answer)
- The PV and PVC must have matching labels
- The PV must be on the same node as the pod that will use the PVC
Correct answer: The PV capacity, access mode, and StorageClass must all satisfy the PVC's request
Kubernetes binds a PV to a PVC only when the PV's capacity is at least as large as requested, the access modes overlap, and the StorageClass names match.
Question 6: Which field on a PersistentVolume allows administrators to restrict which PVCs can bind to it?
- spec.claimSelector
- spec.claimRef (Correct answer)
- spec.nodeAffinity
- spec.storageClassName
Correct answer: spec.claimRef
spec.claimRef can pre-bind a PV to a specific PVC by namespace and name, preventing other PVCs from consuming it.
Question 7: When a Kubernetes node is drained, what happens to pods using PersistentVolumeClaims?
- Pods are deleted and their PVCs are released
- Pods are evicted and, if managed by a controller, rescheduled on another node where the volume is reattached (Correct answer)
- PVCs are automatically migrated to another node's local storage
- Pods remain running on the drained node until the PVC is manually unmounted
Correct answer: Pods are evicted and, if managed by a controller, rescheduled on another node where the volume is reattached
During a drain, pods are evicted gracefully; controllers like Deployments or StatefulSets reschedule them elsewhere, and the CSI driver reattaches the volume to the new node.
Kubernetes Container Orchestration Storage Solutions 5
What Kubernetes feature allows storage capacity information to be published so the scheduler can make volume-aware placement decisions?