It's two days before Christmas shutdown, and this IT pilot fish happens to step into a lab -- where she notices an orange fault light blinking on a server's disk array.
"This is a Unix server with two RAID sets, sent to us by a customer," says fish. "Because it's in the lab, it's not regularly seen by the IT staff. Nor is it on a network, so there's no email notification if anything goes wrong."
But clearly something is wrong, so fish sends a message to the person who regularly uses the server. User's reply: "The system seems to tolerate the faulty disk. It just beeps once in a while. As long as it keeps beeping, I think I'm OK."
Fish sends another message explaining that, because it's a RAID set, one disk can fail and things will keep working. But when a second disk fails, he'll be done for.