# Give pods a per-node cache

A named cache is a directory that one or more pods fill with items they
can make again, such as decoded art or fetched files. When a copy lacks
an item, the pod makes it again. A pod that moves to a new node starts
with an empty cache and warms it. A pod that comes back to a node it
ran on before has the items it made there.

The objects are the same two as a
[replicated store](../replicated-store/): a `PersistentVolume` that
names the driver and the handle, and a `PersistentVolumeClaim` that
binds to it. Take the manifests from that guide and give the volume a
name of its own. The access mode is `ReadWriteMany`, because many nodes
mount the one volume read-write, and each node holds its own copy.

No process keeps cache copies in agreement, and a cache does not need
agreement. An item made on one node is not on the next, and a pod on the
next node makes it again. A single-pod cache therefore needs no
anti-affinity. With several pods, each pod warms the copy on its own
node.

The driver keeps no size budget. A cache grows until the workload trims
it or the filesystem that holds the store fills. Every copy shares that
filesystem with every other volume on the node, so a cache that grows
without a trim takes space from them. The
[gauge](../../reference/metrics/) reports each copy's bytes, so a person
can watch a cache grow.