Using a tar pair to move data between two systems, over an NFS link. This is faster than over ssh (ssh isn’t a fast transport layer). Some user wrote a sparse file out. An 11PB sparse file. Which the tar happily … happily I tell you !!! was trying to copy, in its entirety, over to the backup unit. Happily. Took me a quick look to see what was going on. It had copied 9TB of the 11PB file by the time I’d caught it.