My goal is to have a redundant system that will survive drive failure as well as natural disasters. Here is my system:
The central hub is our Mac Mini with two attached drives. On hard drive holds our files including iPhoto. Another drive backs up everything via Time Machine in the usual hourly pattern.
Chronosync backups up my MBA, my wife’s MBP and the kid’s late ’06 iMac to the Mac Mini once a day to the external files drive.
The Mac Mini and external files drive is backed up offsite via Crashplan. It does this mostly at night.
I came close to buying a Drobo. I did not want to spend that much money and found a couple of nice G-Drives on close out at Best Buy.
Works for me.