Hard drive auto copy

[xhxhxhx]

I am in the process of turning my RPi into a personal cloud server. I am using seafile. I have the main HDD where the files copy but I want to make those files auto copy to a second hard drive. I want the second HDD to be an auto backup for my cloud server. How can I go about doing this?

[elatllat]

http://ubuntuforums.org/archive/index.php/t-502864.html

rsync -a