OptionalglobalGlobal is how much space of a Filesystem volume should be reserved for overhead. This value is used unless overridden by a more specific value (per storageClass)
OptionalstorageStorageClass specifies how much space of a Filesystem volume should be reserved for safety. The keys are the storageClass and the values are the overhead. This value overrides the global value
FilesystemOverhead defines the reserved size for PVCs with VolumeMode: Filesystem