[dnanian]

In general, if you want to make a SuperDuper! backup directly to a drive that has data on it, you should partition it -- one partition should have the SuperDuper! backup, and the other should have your data.

You can also use a disk image -- typically a sparse one -- to store a backup side-by-side with data. (See the FAQ "How do I update an image?" for more about this.)

There is a trick you can use, though.

(Disclaimer for anyone looking in: BE CAREFUL IF YOU TRY THIS. If you do it wrong, it won't work.)

If you create a symlink on the source drive that points to the folder on the destination, we will *not* overwrite that folder with the link (or touch it). So, assuming the folder is called "Retrospect Backups", and is in the root of the drive, and your external drive is called "External", in Terminal you'd say:

ln -s "/Volumes/External/Retrospect Backups" "/Retrospect Backups"

That would create a symlink, in the boot drive, to the "Retrospect Backups" folder on the external, and -- when we see that -- we'll skip that folder when you do anything OTHER than an "Erase, then copy".

You can't use an alias, so don't try. But any program that creates symlinks will work, if you don't want to use Terminal.

Does that help?