I have a removable disk drive (RD1000 from Dell), and I am looking for backup software that will allow me to backup every night, and every morning switch to the alternate disk. There is only one directory structure to back up, what I want is two copies, one which I will take home with me every night, one which will be backing up every night, and when I get in in the morning, I will switch them.

So for instance I have disk "a" and disk "b". On Monday night I want to go home with disk "a" and leave disk "b" in the drive, so that a scheduled back up will be written to it. On Tuesday morning I will come in and swap disks, and I will take "b" home that night, leaving "a" for the backup. And so on for the remainder of the week.

FOSS software preferred, Freeware acceptable, paid software as a last-ditch effort.

Thanks in advance.