def _init_driver(self, shard_id):
"""Given a shard name, returns a storage driver.
:param shard_id: The name of a shard.
:type shard_id: six.text_type
:returns: a storage driver
:rtype: marconi.queues.storage.base.DataDriver
"""
shard = self._shards_ctrl.get(shard_id, detailed=True)
conf = utils.dynamic_conf(shard['uri'], shard['options'])
return utils.load_storage_driver(conf, self._cache)
