3 ms·
Once you decide that absolute reliability is unattainable, you can instead aim for sufficient redundancy. It’s not perfect, but with enough safe guards in place
by jchw 6y ago
Once you decide that absolute reliability is unattainable, you can instead aim for sufficient redundancy. It’s not perfect, but with enough safe guards in place it may very well be good enough.
- microcolonel 6y agoSoftware is not always like hardware though: the same software failure can cascade across redundant instances rapidly just as easily as it affects the primary.
- jchw 6y agoThe same hardware failure can cascade too; redundancy alone is not a panacea, you need some safeguards. Ideally, nothing should fully trust anything else.
- microcolonel 6y agoMaybe cascade was the wrong word. I meant that if you pop in a hot spare and it's running the same software, there's a good chance it will encounter the same issue, sometimes immediately.
- perl4ever 6y agoIn some cases redundant software is developed independently by different teams to the same spec; I think I read about that with the Space Shuttle. How correlated are your layers of swiss cheese...?
- perl4ever 6y agoI was just reading that they design the rocket so that one engine could explode without affecting the others (hopefully) and they test the engines by dropping a nut or bolt or something in, which is not something rocket engines normally can tolerate.