When PersistentVolumeClaim is created using Digitalocean's custom StorageClass, it automatically creates the volumes (which is great) but assigns them random names (such as pvc-1c63892a-4319-444b-8880-960ca612d1d6). Initially I created the volumes manually through the Digitalocean interface and then assign those volumes by ID to a VolumeClaim; the problem with this is that if the node was deleted or recycled, the reassignment of the volume to the new node had to be manual. Anyway, the great of my initial approach was that the billing was very clear: in the details you could see the consumption generated by each volume with a descriptive name.
