From Anonymous, Rinkworks
A friend at work had to visit a police station to work on a Clipper database recording parking fines. Before he started work he made sure to check that the staff had a backup of the database in case anything went wrong.
Cop: "Oh yes, every evening we back it up onto a floppy disk and take it over to the other building and lock it in a fire-proof safe."
"Very good," said my colleague, impressed at their security-consciousness -- if only all our customers could be so efficient! But then something they'd said made him pause. "Wait a minute - did you say a floppy disk? You mean you back up the whole database onto a single diskette?"
Cop: "Yes, that's right. Just one."
Colleague: "But this diskette can only hold 1.44 Mb of data -- you've got over ten megabytes in this system. What exactly do you do to make the backup?"
So they showed him.
Every day they'd religiously inserted a fresh diskette into the drive, typed "FORMAT A:", and, "backup complete," they deposited the newly formatted, but quite empty, diskette in the safe.
Before starting his work, my friend showed them how to really make a backup, which was fortunate for my friend, if not for the local parking offenders, because a week later the PC in question suffered a complete hard-drive failure.