'Return size of volume to be managed by manage_existing.
We expect a volume name in the existing_ref that matches one in Purity.'

@pure_driver_debug_trace
def manage_existing_get_size(self, volume, existing_ref):

    volume_info = self._validate_manage_existing_ref(existing_ref)
    size = self._round_bytes_to_gib(volume_info['size'])
    return size
