Once, some people who managed many security cameras called Raccoon in the darkest and quietest part of the night, waking him from a sound sleep.
"Help!" they said, "we let a contractor perform updates on a pair of database servers that store metadata about the videos the security cameras make! Now, they won't come back on!"
Raccoon yawned and rubbed his eyes. Even though he was sleepy, he knew this was a big problem. These two servers were exact copies of each other, so that even if one was broken the other would continue working and the cameras would be able to keep talking to the database. But if neither of them would come on, the cameras would have nothing to talk to and lots of things would break.
Raccoon logged in and looked around the servers. He knew the servers had to share a lot of information with each other. He quickly figured out this was part of the problem! Something had gone wrong and the servers were logging into one another and telling each other to shut off, like two blue jays shouting at each other to be quiet.
Raccoon changed the password of one of the servers so the other one could no longer get into it and shut it down. He went into the server and made it stop shouting. He found some other problems and fixed those. Then he did the same things to the second server.
The database came back up and the cameras started working again. "I'm glad I could solve that problem," Raccoon said, and went back to sleep.