Storage
Module infographic
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Revision poster: from claim to disk.

Infographic: the chain from Pod to PVC to PV to the storage backend, access modes, reclaim and binding policies, snapshots and expansion
Click the poster to enlarge it

The left chain shows what depends on what. The right side lists the policies that decide whether a volume can be created, attached and kept.

  1. 1The Pod mounts a claim; the claim binds to a volume.
  2. 2A StorageClass says how to create volumes; a CSI driver talks to the backend.
  3. 3WaitForFirstConsumer provisions the disk in the Pod's zone.
  4. 4RWO is one node, ROX many readers, RWX many writers on a shared filesystem.
  5. 5Retain keeps the data when the claim is deleted.
  6. 6Snapshots, clones and in-place expansion are CSI features; StatefulSets give each replica its own PVC.

Self-check: cover the poster and answer

  • A Deployment's second replica stays Pending on an RWO volume: why, and what are two fixes?
  • What happens to the disk when you delete a PVC whose class says Delete?

A claim asks, a class provisions, a driver delivers.

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