Hint: throttling xtrabackup

Using xtrabackup for copying files can really saturate your disks, and that why we made special option

--throttle=rate

to limit rate of IO per second. But it really works when you do local copy.
What about stream backup ? Even you copy just to remote box with

innobackupex --stream=tar | ssh remotebox "tar xfi -"

, read may be so intensive so your mysqld feels impact, slave getting behind, etc…

For this there is a nice small utility – pv .

With pv you run:

innobackupex --stream=tar | pv -q -L10m | ssh remotebox "tar xfi -" 

and it will limit channel rate to 10 M per second.