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 Throttling backups with |innobackupex|
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Although |innobackupex| does not block your database's operation, any backup can add load to the system being backed up. On systems that do not have much spare I/O capacity, it might be helpful to throttle the rate at which |innobackupex| reads and writes |InnoDB| data. You can do this with the :option:`--throttle` option.

This option is passed directly to |xtrabackup| binary and only limits the operations on the logs and files of |InnoDB| tables. It doesn't have an effect on reading or writing files from tables with other storage engine.

One way of checking the current I/O operations at a system is with :command:`iostat` command. See :ref:`throttling_backups_xbk` for details of how throttling works.

.. note:: 

   :option:`innobackupex --throttle` option works only during the backup phase, ie. it will not work with :option:`innobackupex --apply-log` and :option:`innobackupex --copy-back` options.

The :option:`--throttle` option is similar to the ``--sleep`` option in ``mysqlbackup`` and should be used instead of it, as ``--sleep`` will be ignored.
