We want to rotate our external hard drives to an off site location for data security. Windows 7 Backup works flawlessly until I replace the external hard drive with another identical drive. At that point I have to reconfigure W7 backup, telling it to write to the replacement drive. If I connect the original external drive, I have to set up the backup again. This is a different behavior than what happens on Windows Server 2008 R2. The W2K8 backup program allows you to initialize multiple external hard drives so that if any one of them is connected, the backup gets written to it. Is there a way to tell Windows 7 Backup to use any one of a series of external hard drives? Why does it require reconfiguration every time the external hard drive is changed?

Unfortunately the windows 7 backup package is not as advanced as that which comes with server. I don't believe you will be able to achiever your goal with windows 7 backup. I would LOVE to see the same backup system from 2k8 ported to 7. It's brilliant.

You can try to assign a same drive letter for these external hard drives.Arthur Xie - MSFT

One other option you can use is the Seagate Go Dock. This would of course require you to purchase new backup drives, but the dock is a direct usb dock that automatically assigns the same drive letter to each drive you load into it. This way you can swap drives daily and each drive appears as the same to the backup software.