How to backup freenas data storage ?

hi all,

I already have one freenas box with 2 hdd set to mirror.

then i want to backup all data on that freenas every night to another place ( perhaps another freenas box )
which the best way to do that ?
i already attach the pic of my storage with this post .. please check it out .

View attachment 5149 View attachment 5150

i just think about using Rsync , is it possible to rsync folder "FILE_SERVER" to another freenas box ? so the subfolder inside folder FILE_SERVER will be copied to...

How to backup freenas data storage ?