# What a volume here can and cannot do

**`local-path` is the only StorageClass and it is the default.** *Everything
below follows from that, and none of it is negotiable without adding replicated
storage, which is not deployed.*

---

## A volume belongs to one machine, permanently

**Every volume carries a hard affinity to the node backing it.** *So anything with
a volume inherits the availability of one machine, and the only variable left is
which one.*

> **Anything that assumes it can be rescheduled freely is assuming something this
> cluster does not provide.**

**Choose the node deliberately rather than letting it land.** *A volume that
lands somewhere by accident becomes a single point of failure nobody picked —
which happened once, and the service could not come back when that node died.*

## A volume cannot be grown

**`ALLOWVOLUMEEXPANSION` is false.** *Growing one means dump and restore, or
manual migration — not an edit.*

**Size with headroom.** *This is the constraint most likely to be discovered
late.*

## Where this does not bite

**Postgres run by the operator is shared-nothing** and replicates at the database
level, so a cluster of two survives losing a node **even though neither volume
can move.** *The node affinity is intended there rather than tolerated.* See
[databases](databases.md).

## What would change this

**Replicated storage** — Longhorn being the obvious candidate — **is deliberately
not deployed.** *A substantial thing to operate on three nodes, and the downtime
has not yet cost anything.* **Revisit when it does.**

---

## Checking this is still true

**Verified 2026-09-03.**

```sh
kubectl get sc                             # local-path, default, ALLOWVOLUMEEXPANSION false
kubectl get pvc -A
kubectl get pv -o custom-columns=NAME:.metadata.name,NODE:.spec.nodeAffinity
```