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How Complex Systems Fail (1998)

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Re: How Complex Systems Fail (1998)

#31

Post by tptacek »

sandeepkd wrote: post #21

Overall a good collection on the complex systems, somehow it missed the part how complex system came into the existence in the first place itself. > Human expertise in complex systems is constantly changing I feel this is single most important factor responsible to both making system complex and at the same time improving them depending on who the people are and how they take failures and breakdowns. I find it funny…

Literally the first item in the list addresses the necessity of complexity in the systems it's discussing.

Re: How Complex Systems Fail (1998)

#32

Post by YZF »

jedberg wrote: post #22
AlotOfReading wrote: post #12

Earlier quoted context omitted.

I've always struggled to apply this to the systems I work on. If the system fails, someone potentially dies, though in practice they've never been more than hospitalized. To avoid that, huge amounts of effort are expended on failure modelling and testing, but that doesn't eliminate unknown unknowns. That discrepancy has made front page news a couple times.

When I was at Netflix and reddit, one thing I said often was, "Luckily, we are not a bank". And it sounds like you are working on even more critical systems than that. Chaos engineering doesn't really apply to data critical or safety critical systems. You can't just break them in the real world to see how they fail. You have it exactly right -- it has to be modeled and tested in lab conditions. Safety critical system…

It's still a tool in the tool box. Somewhat analogous to accelerated life testing in non-software products. You induce conditions that make failures more likely to occur.

Re: How Complex Systems Fail (1998)

#34

Post by pdonis »

tptacek wrote: post #16

I'm a broken record on how important I think this document is, and that it's hard to appreciate it until you've had extended experience with complex systems actually failing. The most commonly cited subtext or thrust of it is that "root cause analysis", at least on complex systems, is a fools errand. Something goes wrong, say, in a distributed lock system, and your whole deployment system enters a metastable failure…

> "root cause analysis", at least on complex systems, is a fools errand.

Not when properly understood--which, to be fair, it often isn't. The proper purpose of root cause analysis is to answer the question: does this failure mean I need to change something about this system? If the answer turns out to be yes, the thing that you need to change gets called the "root cause" of the failure. Of course that's a misnomer, strictly speaking, but that doesn't mean you answered the actual question wrong.

Re: How Complex Systems Fail (1998)

#35

Post by DrewADesign »

pdonis wrote: post #34
tptacek wrote: post #16

I'm a broken record on how important I think this document is, and that it's hard to appreciate it until you've had extended experience with complex systems actually failing. The most commonly cited subtext or thrust of it is that "root cause analysis", at least on complex systems, is a fools errand. Something goes wrong, say, in a distributed lock system, and your whole deployment system enters a metastable failure…

> "root cause analysis", at least on complex systems, is a fools errand. Not when properly understood--which, to be fair, it often isn't. The proper purpose of root cause analysis is to answer the question: does this failure mean I need to change something about this system? If the answer turns out to be yes, the thing that you need to change gets called the "root cause" of the failure. Of course that's a misnomer, s…

I don’t blame people for being confused about the term in software — it’s a bit more straightforward in manufacturing, for example.

That said, if you look at a system that failed and determine a root cause analysis is pointless, you may have just stumbled upon your root cause.

Re: How Complex Systems Fail (1998)

#37

Post by GolfPopper »

jedberg wrote: post #26
eskimobloood wrote: post #23

Earlier quoted context omitted.

> One of the big issues schools and pedagogy in general struggle with is that our environment is far too safe in too many ways. For kids there is too few ways to learn from failures. Its cause we already learned from our failures and make the world a safer place. In my youth we climbed on trees, one of my friend fall down broke his arm, the doctor couldn't fix it and he can not move the hand for the rest of his live.…

There's a fine line between "we made the world safer" and "we made the world too constricting to learn". I would like my kids to be allowed to fail a bit more often, while still staying safe. I think we've swung too far in the safe direction.

The difficult part is judging where that "happy medium" is. (And then how to get there.)

Re: How Complex Systems Fail (1998)

#38

Post by jasode »

tptacek wrote: post #16

I'm a broken record on how important I think this document is, and that it's hard to appreciate it until you've had extended experience with complex systems actually failing. The most commonly cited subtext or thrust of it is that "root cause analysis", at least on complex systems, is a fools errand. Something goes wrong, say, in a distributed lock system, and your whole deployment system enters a metastable failure…

>The most commonly cited subtext or thrust of it is that "root cause analysis", at least on complex systems, is a fools errand.

It's only an issue when people take that phrase very literally. People have common sense to understand that things have multiple causes and a chain of events. NASA has "Root Cause Analysis" (singular) all over various official documentation and it doesn't stop them from understanding that the failed O-rings were not the single root cause of the Challenger explosion. Another cause was management normalizing the deviations of previous unsafe datapoints of prior launches which let them greenlight the launch in freezing temperatures. Another cause was the unrealistic flight schedules which can subconsciously pressure management into normalizing dangerous deviations. It wasn't The Rogers Commission that found the multiple causes; it was NASA engineers and management themselves explaining the multiple causes as they were interviewed by the Rogers Commission members.

For whatever reason, alternative jargon such as "Root Causes Analysis" (plural) or "Proximate and Distal Causes Analysis" isn't as widely used.

Re: How Complex Systems Fail (1998)

#39

Post by _boffin_ »

tptacek wrote: post #16

I'm a broken record on how important I think this document is, and that it's hard to appreciate it until you've had extended experience with complex systems actually failing. The most commonly cited subtext or thrust of it is that "root cause analysis", at least on complex systems, is a fools errand. Something goes wrong, say, in a distributed lock system, and your whole deployment system enters a metastable failure…

Check out the book called, The Logic of Failure. I think you’ll like it
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