def _create_volume(self, deployer):
        api = deployer.block_device_api
        profile_name = self.metadata.get(PROFILE_METADATA_KEY)
        size = allocated_size(allocation_unit=api.allocation_unit(),
                              requested_size=self.maximum_size)
        if profile_name:
            return (
                deployer.profiled_blockdevice_api.create_volume_with_profile(
                    dataset_id=self.dataset_id,
                    size=size,
                    profile_name=profile_name
                )
            )
        else:
            return api.create_volume(dataset_id=self.dataset_id, size=size)
Create the volume using the backend API. This method will create the
dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/agents/blockdevice.py/CreateBlockDeviceDataset._create_volume