Exercise 1: Why "No One Complained" Is What a Silent Failure Looks Like — Possible Solution ==================================================================== WHAT THIS CHAPTER SAYS ------------------------------ Per this chapter, "many of the worst backup failures are completely silent: a scheduled job that stopped triggering weeks ago produces no error at all, because it simply never runs - not because it fails loudly and gets noticed. An absence of complaints is exactly what an unnoticed failure looks like from the outside." WHY A LOUD FAILURE AND A SILENT ONE PRODUCE THE SAME OUTWARD APPEARANCE ------------------------------ A working backup system produces no complaints because everything is fine. A silently broken one - a job that stopped running weeks ago, or notifications going to an abandoned inbox, as in this chapter's own example - also produces no complaints, but for the opposite reason: no one who could complain even knows there's a problem. From outside either system, the observable signal (no complaints, no visible errors) is identical. WHY THIS MAKES "NO COMPLAINTS" WORTHLESS AS EVIDENCE ------------------------------ Evidence is only useful if it can distinguish between two possible states. Since both "genuinely working" and "silently broken" produce the exact same absence of complaints, that absence can't be used to tell which state you're actually in - it's consistent with both, which means it doesn't actually confirm either one. WHY THIS CONNECTS DIRECTLY TO log1's "EVIDENCE OVER GUESSWORK" PRINCIPLE ------------------------------ Per this chapter, this is "the same 'evidence over guesswork' discipline log1 built this whole subject around - verify by actually reading the record, not by assuming the record must say what you expect." Treating silence as reassurance is a guess dressed up as evidence; actually reading the job's own log, as this chapter does next, is the only way to find out which of the two identical-looking states is the real one. WHY THIS WORKS AS AN ANSWER ------------------------------ It quotes the chapter's own reasoning, explains why a working system and a silently broken one look identical from the outside, and explains why that identical appearance is exactly what makes "no complaints" useless as proof of anything.