So I'm using a 250GB external hard drive with superduper! to create backups. I'm keeping 3 copies and progressively erasing the oldest one to make space for the newer backup copy.
The problem is, my hard drive isn't freeing up space when I erase the previous backup. Let's say I have 100GB available and my backups are 40GB each. I erase the last copy and create a new backup; I should now be at about 100GB again except that when I get the info on my external HD, I'm told that I only have 60GB available as if my old backup copy didn't get erased.
In the past I've remedied this by formatting the drive, but I don't want to have to do that because I obviously don't want to trash all my backups. My HD is formatted in HFS+ with journaling enabled (so that my backup copies can be bootable). Any ideas?