Domain 4 · Storage | Asterrr's Handbook

10% of the exam. Creating PersistentVolumes, PersistentVolumeClaims and StorageClasses, getting a claim to bind, and mounting it into a Pod.

Domain 4 is the smallest domain, but its tasks are quick points if you know the YAML by heart. Expect one or two tasks that hand you a half-finished setup: a claim stuck in Pending, a PV that won't rebind after its claim was deleted, a class that should be the default, or a volume that needs to grow. Nearly every one is solved by lining up five fields between a PV and a PVC.

Competency	What it's really asking	Pages
4.1 StorageClasses and dynamic provisioning	Write a StorageClass, make it the default, pick the binding mode, allow expansion, and know which CSI driver does the work	StorageClasses
4.2 Volume types, access modes and reclaim policies	Pick between ephemeral and persistent volumes, choose RWO, ROX, RWX or RWOP, and say what happens to data when the claim goes away	PersistentVolumes and claims
4.3 PVs and PVCs	Create a PV by hand, write a claim that binds to it, mount it into a Pod, and recover a `Released` volume	PersistentVolumes and claims

What connects Domain 4 to the rest of the exam:

CSI drivers are one of the three plug-in interfaces covered in Extension interfaces.
StatefulSets create one claim per replica from volumeClaimTemplates; the workload side is in Self-healing workloads.
A Pod stuck in Pending because of an unbound claim is a classic application troubleshooting task.

Matching on size alone

A claim for 1Gi doesn't bind just because a 5Gi PV is Available. The class name, access mode, volume mode and any label selector must match too, and an empty class on one side is not the same as an unset class on the other. When a claim stays Pending, compare the PV and PVC field by field with kubectl get pv,pvc -o wide before you change anything else.