Storage for StatefulSets: volumeClaimTemplates

Storage / Guide 73 of 103 / Intermediate

• Kubernetes1.36.4
• Cluster4 nodes
• Runtimecontainerd 2.2.6
• CNICalico v3.32.1
• TimeAbout 35 min

PVC names are generated deterministically. That predictability is the feature, not an implementation detail.

• Provisionerrancher.io/local-path

This guide includes

Use this when every replica of a workload needs a disk of its own. This matters because volumeClaimTemplates binds a volume to the ordinal rather than to the Pod, and nothing you do to the StatefulSet will ever delete those claims for you.

• using volumeClaimTemplates to give each replica its own claim, named deterministically by ordinal
• deleting a Pod and watching the same volume come back attached to the same ordinal
• scaling up to get a new claim, then scaling down and finding the old one still there
• deleting the StatefulSet outright and finding every claim still present

Before you start

• The StatefulSets guide, for stable identity and ordered rollout.
• The dynamic provisioning guide, since each generated claim provisions a volume.
• The reclaim policies guide, for what happens to the claims this guide leaves behind.

1. 1

   volumeClaimTemplates, and the names it generates

2. 2

   The volume belongs to the ordinal, not to the Pod

3. 3

   Scaling up creates a claim; scaling down does not remove one

4. 4

   Deleting the StatefulSet keeps them too

Official sources

• StatefulSets
• StatefulSet volumeClaimTemplates
• PersistentVolumeClaim retention
• Run a replicated stateful application
• Scale a StatefulSet
• Delete a StatefulSet