I have an external hard disk drive connected to my Mac Pro (4,1->5,1, HS 13.6) via USB. It's a backup volume with two partitions and usually unmounted. Each evening at 19:00 and 19:15 CCC mounts it and starts the backup process to mirror two volumes. I was stunned to hear the backup HDD being mounted just a few minutes ago at 17:30 and the drive sounding busy. I kind of panicked and unmounted the backup drive immediately. Does anyone have an idea for an explanation?