Help with backing up my usb drives

[Socorso]

I have two USB drives hooked up to my AEBS. I need to back this data up on a regular basis (without my intervention). I've tried a number of software options, but none seem to find the drives unless I constantly point them out.
I currently use a drive connected to my iMac using Chronosync for the USB drives and timemachine for the iMac.

Does anyone have a better solution?

 

[angelwatt]

I use CCC for backing up pretty much all of my drives, including external ones.