EX280 Storage And Persistent Volumes Practice Test 4 — 15 Questions

Question 1

Which object defines the parameters used by a storage provider to take snapshots of persistent volumes in OpenShift?

Accepted Answer

VolumeSnapshotClass. VolumeSnapshotClass is the cluster-scoped object that defines the CSI driver and deletion policy used when taking snapshots of PersistentVolumes. It plays the same role for snapshots that a StorageClass plays for provisioning — it tells the snapshot controller which driver to invoke and how to handle the resulting VolumeSnapshotContent.

Answer

SnapshotterConfiguration

Answer

StorageClass

Answer

VolumeSnapshotContent

Question 2

What is the effect of setting 'allowVolumeExpansion: true' in a StorageClass?

Accepted Answer

It permits users to increase the storage size of PVCs created from this StorageClass.. Setting allowVolumeExpansion: true in a StorageClass allows users to increase the size of PVCs created from that StorageClass. This enables online expansion of volumes, provided the underlying storage provider supports it.

Answer

It automatically shrinks PVCs when storage usage drops below 50%.

Answer

It allows multiple pods to write to an RWO volume simultaneously.

Answer

It allows the cluster to automatically scale the number of worker nodes based on storage demand.

Question 3

An administrator wants to verify which CSI driver plugins are registered and active in an OpenShift cluster. Which cluster-scoped resource should they query?

Accepted Answer

csidrivers.storage.k8s.io. The cluster-scoped resource that lists registered CSI drivers is csidrivers.storage.k8s.io. This resource represents the CSI drivers that are registered with the Kubernetes cluster and provides information about their capabilities, such as whether they support attach/detach operations. Querying this resource shows which CSI drivers are active and available for use.

Answer

volumesnapshotclasses.snapshot.storage.k8s.io

Answer

storageclasses.storage.k8s.io

Answer

csinodes.storage.k8s.io

Question 4

Which component in OpenShift is responsible for watching PersistentVolumeClaims and dynamically provisioning PersistentVolumes when supported by a StorageClass?

Accepted Answer

kube-controller-manager. The kube-controller-manager runs the PersistentVolume controller, which watches for PersistentVolumeClaims that reference a StorageClass with a provisioner and dynamically creates matching PersistentVolumes. This is the component that implements dynamic provisioning in both Kubernetes and OpenShift. Without it, PVCs would remain Pending unless an admin manually pre-provisioned a PV.

Answer

kube-scheduler

Answer

crio

Answer

etcd

Question 5

A user creates a PVC, but the storage backend fails to provision the volume. Where can the administrator look to find detailed error messages emitted by the external provisioner controller?

Accepted Answer

Review the logs of the CSI external provisioner controller pod in its management namespace.. When a PVC fails to provision, the external provisioner sidecar (e.g., csi-provisioner) running alongside the CSI driver controller is the component that actually calls the storage backend's CreateVolume API and logs the resulting errors. In OpenShift, CSI controller pods run in the driver's management namespace (typically openshift-cluster-csi-drivers or the operator's namespace), so reviewing that pod's logs reveals the detailed backend error messages.

Answer

Run 'oc adm diagnostics storage'.

Answer

Inspect the container image registry logs.

Answer

Check /var/log/messages on the control plane nodes.

Question 6

What is the primary difference between PersistentVolumes (PVs) and PersistentVolumeClaims (PVCs)?

Accepted Answer

PVs represent actual cluster storage resources, while PVCs represent user requests for storage.. PersistentVolumes (PVs) are cluster-level storage objects that represent the actual backing storage (NFS, iSCSI, cloud disk, etc.) provisioned by an admin or dynamically by a StorageClass. PersistentVolumeClaims (PVCs) are namespace-scoped requests from a user/pod for a certain size and access mode, which the control plane binds to a matching PV. This separation of 'supply' (PV) from 'demand' (PVC) is the core abstraction in Kubernetes/OpenShift storage.

Answer

PVs only support block mode, while PVCs only support filesystem mode.

Answer

PVs are created by developers, while PVCs are created by cluster administrators.

Answer

PVs are namespace-scoped, while PVCs are cluster-scoped.

Question 7

An administrator needs to back up application data stored on an OpenShift PVC. Which object must be created to initiate the snapshot process via the CSI driver?

Accepted Answer

VolumeSnapshot. The VolumeSnapshot object is the user-facing custom resource that requests a snapshot of a PersistentVolumeClaim (PVC) when using a CSI driver that supports snapshotting. It is created by the administrator to initiate the snapshot process, and it triggers the creation of a VolumeSnapshotContent object that represents the actual snapshot on the storage backend. This is part of the Kubernetes CSI snapshot API, which OpenShift supports.

Answer

BackupCR

Answer

VolumeSnapshotContent

Answer

StorageSnapshot

Question 8

Which command is used to delete a PersistentVolumeClaim named 'my-app-pvc' in the current project?

Accepted Answer

oc delete pvc my-app-pvc. 'oc delete pvc my-app-pvc' is the correct syntax to remove a PersistentVolumeClaim in the current project. The 'oc delete' verb works uniformly across resource types, and 'pvc' is the accepted short name for PersistentVolumeClaim. The current namespace is used unless -n is specified.

Answer

oc remove pvc my-app-pvc

Answer

oc destroy pvc my-app-pvc

Answer

oc prune pvc my-app-pvc

Question 9

A developer wants to ensure that a pod's temporary storage does not exceed 2Gi and that the pod is terminated or throttled if it exceeds this limit. Where should this ephemeral storage limit be declared?

Accepted Answer

In the container's spec.resources.limits under 'ephemeral-storage'.. Ephemeral storage limits are declared in the container's spec.resources.limits under the 'ephemeral-storage' key, just like CPU and memory. This causes the kubelet to enforce the limit by evicting the pod when local ephemeral storage usage exceeds the configured value. The limit applies to the container's writable layer, emptyDir volumes, and logs, making it the correct place for a 2Gi cap.

Answer

In the emptyDir volume specification under 'sizeLimit'.

Answer

In the StorageClass under 'parameters.ephemeralLimit'.

Answer

In the persistentVolumeClaim under 'spec.ephemeral'.

Question 10

Which resource represents the physical or cloud storage provisioned in the cluster by an administrator, independent of any user namespace claims?

Accepted Answer

PersistentVolume. A PersistentVolume (PV) is the cluster-scoped resource that represents actual storage provisioned by an administrator — an NFS export, EBS volume, or Ceph RBD image — and exists independently of any namespace. It is bound to a PersistentVolumeClaim (PVC) when a user requests storage, but the PV itself is not owned by or scoped to a user namespace.

Answer

StorageClass

Answer

PersistentVolumeClaim

Answer

PodVolume

Question 11

A pod fails to start, and the event log shows a Multi-Attach error for volume 'pvc-xyz'. What is the root cause of this error?

Accepted Answer

A ReadWriteOnce volume is attempting to be attached to a second node while still attached to the first.. The Multi-Attach error occurs when a ReadWriteOnce (RWO) volume is already attached to one node and a pod on another node tries to attach it. RWO volumes can only be attached to a single node at a time. This is common with block storage like AWS EBS or GCE PD.

Answer

The PVC storage class has volumeBindingMode set to Immediate.

Answer

The storage backend has run out of physical disk capacity.

Answer

The CSI driver pod has crashed on the master node.

Question 12

A cluster administrator needs to inspect the current bindings and capacities of all PersistentVolumes across the entire OpenShift cluster. Which CLI command should be used?

Accepted Answer

oc get pv. PersistentVolumes (PVs) are cluster-scoped resources in OpenShift/Kubernetes, so 'oc get pv' lists every PV in the cluster along with its capacity, access modes, reclaim policy, status, and claim binding. Because PVs are not namespaced, no --all-namespaces flag is needed or accepted. This single command gives the administrator the complete cluster-wide view of bindings and capacities requested.

Answer

oc get pvc --all-namespaces

Answer

oc describe storage

Answer

oc get volume

Question 13

An administrator is configuring topology-aware storage provisioning. A StorageClass uses volumeBindingMode: WaitForFirstConsumer. When is the PersistentVolume actually created?

Accepted Answer

When the scheduler places the pod referencing the PVC onto a specific worker node.. With volumeBindingMode: WaitForFirstConsumer, the PV is not provisioned when the PVC is created. Instead, the scheduler delays binding until a pod using the PVC is scheduled, so it can pick a node and provision the volume in the correct topology zone. The PV is created at that point, ensuring the volume lands in the same zone as the pod.

Answer

When the PVC object is successfully created in the namespace.

Answer

When the user executes 'oc adm pv create'.

Answer

When the CSI driver operator starts up during cluster bootstrap.

Question 14

A developer deploys an application that mounts a PVC in read-only mode inside the pod specification. How is this configured in the Pod's volumeMounts?

Accepted Answer

Set readOnly: true in the container's volumeMounts entry.. Read-only mounting of a PVC inside a pod is set per-container via `readOnly: true` in the volumeMounts entry. This tells the kubelet to mount the volume read-only for that container, regardless of the PVC's access modes.

Answer

Set accessModes to ReadOnlyMany on the PVC object.

Answer

Set volumeMode: ReadOnly in the PVC spec.

Answer

Annotate the PVC with 'volume.beta.kubernetes.io/readonly'.

Question 15

Which YAML key in a StorageClass definition specifies the CSI plugin responsible for provisioning the storage?

Accepted Answer

provisioner. The provisioner field in a StorageClass identifies the CSI driver (or in-tree provisioner) responsible for dynamically provisioning PersistentVolumes. For CSI-based storage, its value is the driver name registered by the CSI plugin, such as ebs.csi.aws.com or csi.ceph.com. Without a valid provisioner, the StorageClass cannot create PVs.

Answer

storagePlugin

Answer

plugin

Answer

driverName