Oops. Was that important?

It's a common mistake to assume that if a process is mission critical then it must be required every single day. While I agree that anything critical should be monitored at all times and incidents like "It hasn't been doing anything all month" should have been responded to long before they got to that point, it's not unusual to be doing different things at different times and for that to affect the apparent severity of an issue. If you are managing the cash registers at an amusement park and don't see any transactions for all of January and February, that's not a problem because the park is closed all winter. If you don't see transactions for one hour in the middle of the afternoon in July then it's time to hit the apocalypse alarm and start summoning horsemen. Many years ago at a former employer who has long since gone out of business, someone found what looked like a spare PC sitting on a desk in the server room, turned on but with no monitor or keyboard. He investigated it, found it was running only an old desktop operating system with some proprietary fax and printer software, and decided that it probably wasn't important. He asked about the "weird fax server" that he had found and nobody else thought it was important, so one afternoon he simply shut it down. Nobody screamed, nothing broke, so he left it shut down for another week. By the end of the month there were still no complaints so he pulled it out of the server room and put it into storage. Two more months passed and then he was convinced that this old PC clearly served no purpose and had it decommissioned. Because he took a certain degree of pride (and occasionally joy) in his job, the decommissioning process involved hard drive platters, a drill press, and occasionally a trip out to the firing range for some target practice. Once every storage device had been thoroughly destroyed he shipped the remains off to an electronics recycling firm who either broke it down into its component atoms, or slapped a "Gateway 2000" sticker on it and resold it as a new PC. Either way, he was quite happy that he had followed every reasonable precaution and confident that he had waited far longer than he ever needed to to ensure that he wasn't scrapping vital hardware. Which is why it was such a big surprise when the Very Expensive Proprietary Software which the company relied on, after having failed to contact its license server for three months in a row, suddenly stopped working and instead demanded that the users contact the sales department of a company which had gone out of business two years earlier to acquire a proper license. But, hey, at least nobody responded to the "scream test", so it couldn't have been all that important, right?