[dnanian]

Syzygies is correct, but another option is to partition your drive into a "backup" and "data" partition, keeping the two uses separate. That would allow you to write directly to the drive, and thus you could boot directly from the backup as well.

The User's Guide (in the Help menu) goes into the various options in some detail. The relevant section is linked right off the first page -- Storing a backup alongside other files on a destination drive.

Hope that helps!