Google ACE Practice Question: A team is migrating a stateful application with…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  A HostPath volume pointing to a directory on the node

  Why it's wrong here

  A HostPath volume mounts a file or directory from the specific node where the Pod is currently running into the container. This storage is local to that node: if the Pod is rescheduled to a different node (due to a node failure, rolling update, or scale-down), the new node's path will not contain the data written on the old node. HostPath also creates a security risk because it can expose sensitive host filesystem paths to containers. It is rarely appropriate for production stateful workloads, except for certain system-level tools that are node-bound.

• ✗

  A ConfigMap mounted as a volume

  Why it's wrong here

  A ConfigMap mounted as a volume is designed for injecting configuration data (e.g., environment variables, config files) into Pods, not for storing application state. ConfigMap volumes are presented as read-only mounts by Kubernetes, so an application cannot write to them at runtime. Additionally, ConfigMap data is stored in the cluster's etcd rather than on a persistent storage backend, making it unsuitable for any workload that requires durable, writable storage. Attempting to use a ConfigMap for state will result in write failures and data loss.

• ✓

  A PersistentVolumeClaim backed by a GCE persistent disk StorageClass

  Why this is correct

  A PersistentVolumeClaim (PVC) backed by a GCE persistent disk StorageClass provides durable, network-attached block storage that is provisioned independently of any specific node. When a Pod using this PVC is rescheduled, the underlying PersistentVolume (a GCE PD) is detached from the old node and attached to the new node, preserving all application-written data. This makes it the correct choice for stateful workloads that must survive Pod restarts or node failures. Note that the PD is zonal, so the new node must be in the same zone as the disk.

• ✗

  An emptyDir volume scoped to the Pod

  Why it's wrong here

  An emptyDir volume is created when a Pod is bound to a node and exists only as long as that Pod remains running on that node. If the Pod is deleted or rescheduled to another node, the contents of the emptyDir are permanently erased. It is intended for ephemeral scratch space, such as caches, temporary files, or inter-container sharing within the same Pod, not for data that must persist across Pod restarts or node migrations. Thus it cannot guarantee durability for stateful applications.

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