Uh, that isn't the "O-Ring Theory" I would have expected. The Challenger failed because, while the O-Rings were within tolerances, they shouldn't have been var

Uh, that isn't the "O-Ring Theory" I would have expected. The Challenger failed because, while the O-Rings were within tolerances, they shouldn't have been varying at all. So because they were varying unexpectedly, they inevitably failed. I would claim the corresponding devops theory is "measure everything, know what is measurement noise and what is user activity, and eliminate everything else before it causes an outage". (from Wikipedia: "In one example, early tests resulted in some of the booster rocket's O-rings burning a third of the way through. These O-rings provided the gas-tight seal needed between the vertically stacked cylindrical sections that made up the solid fuel booster. NASA managers recorded this result as demonstrating that the O-rings had a "safety factor" of 3. Feynman incredulously explains the magnitude of this error: a "safety factor" refers to the practice of building an object to be capable of withstanding more force than the force to which it will conceivably be subjected. To paraphrase Feynman's example, if engineers built a bridge that could bear 3,000 pounds without any damage, even though it was never expected to bear more than 1,000 pounds in practice, the safety factor would be 3. If a 1,000 pound truck drove across the bridge and it cracked at all, even just a third of the way through a beam, the safety factor is now zero: the bridge is defective.")