I was reminded today about the worst backup mistake I ever made.

Way back when hard disks were luxuries, I was making a backup of a floppy disk by copying it to another floppy. I verified which disk to copy and which was blank, but while the disk copier was loading, I got them mixed up.

The disk was halfway through quietly formatting away, in the slowest floppy drive ever invented, when I noticed the disk in my hand was the unformatted blank.

Profane lamentations for days.