Normally a storage plane can be backed by a single PVC.
However, if numDevices is defined (>1), it can be backed by multiple PVC.
The helm chart will generate multiple mount points to the PVC named by the plane, postfix.
e.g. for a plane defined as:

The helm chart will expect 2 PVC's to exist, each with a "-<N>" prefix.
i.e. in this case:
data-mystorage-hpcc-localfile-pvc-d1 and "data-mystorage-hpcc-localfile-pvc-1" and "data-mystorage-hpcc-localfile-pvc-2".

The engines will use these multiple devices to stripe logical file partitions over them.
Meaning in the case of Thor, different workers will be writing partitions to different PVC's.

There are two aspects to configuring a system to support this:
1) Define suitable storage accounts, Persistent Volumes and Persistent Volume Claims, that can be referenced by the HPCC planes definitions.
2) Configure a data plane in the HPCC planes definition to reference the common PVC prefix and set numDevices the number of PVCs (as per above example).