Comment by hatchnyc | Hacker News Reader

Comment by hatchnyc | Hacker News Reader

Not a specific piece of software, but a characteristic of a limited percentage of anonymous internal systems--one of the most beautiful things to witness in the realm of design is a system undergoing catastrophic stress when the designers anticipated and planned for such events, and in usually a very short period of time you see the results of extensive planning spool out, design features hidden from view and unappreciated until this moment, kick in and recover/compensate in ways that feel almost magical.

For obvious reasons it is much more common to see this level of design in physical, life-critical systems like aerospace or automotive technology, but you do see it sometimes in software. Well designed services that under heavy load, various kinds of infrastructure failure, attack, or other kinds of scenarios well outside the bounds of normal expected operations intelligently compensate while signaling alerts with precise, useful information, and attempt whatever kind of recovery is possible.

This is hard to anticipate and often thankless to build in advance. It's always a stressful time when this behavior is visible, but it gives me a feeling of admiration for the perhaps long gone employees who built it.

any examples?

Nortel DMS-10 telephony switch springs to mind. They run in landline phone company switching offices amd date back to the early 1970s. Those things are indestructible in the face of all kinds of disasters.

Mercedes has a system on the S-class that uses the sensors to detect a potential impact (e.g. an rapidly approaching vehicle while the car is stationary) and uses the active suspension to "jump" raising the car a few inches just at the moment of impact, apparently slightly reducing the potential for injury.

Many cars and especially planes & spaceships are have tons of systems like this.

I worked on a system that did things like in response to a primary datasource being offline would switch the queries it used to a different database to include substitute data and pass this back to be used instead until the primary store came back online. Three years after it was put in production this happened on one of the company's biggest and most important days of the year, and our SREs were sitting there calmly trying to solve the issue, ended up waiting until late at night to deploy a fix. It would have been reasonable for this service to just rely on the primary source, but we would have been offline for hours if this little trick hadn't been put in place.

>...a different database to include substitute data and pass this back to be used instead

The thing that trips me up about this is how can you ensure that the substitute data is actually useful. Is the substitute data a copy of the primary data? I guess it all depends on the use case...

> raising the car a few inches just at the moment of impact, apparently slightly reducing the potential for injury

I wonder if the occupants of the other car benefit in any way...

Haha, maybe not? Since their car would tend to go underneath, although the footage I've seen always shows the other vehicle hitting from the side with the hood sliding slightly beneath the Mercedes...it does seem from watching that would give other vehicle slightly more space to dissipate the impact energy.

Now if they had only bought a Mercedes as well, they could have chosen the self-breaking option to avoid the collision in the first place.

The old joke about Mercedes cars goes: what car, it rusted away, there’s no car.

I’m on my phone so I can’t find a better source, but Mercedes plays a sound to prevent hearing loss during a car crash.

https://nowiknow.com/the-special-sound-a-mercedes-benz-makes...

One that I've always thought is really cool since I heard about it is the base of street signs. Instead of being cemented into the ground, signs are commonly bolted to a base so that they'll break away when hit. Some even have an incline that will throw the sign up and over your car. After learning this, I've started paying attention to signs I pass on walks or while driving and it's crazy how they are everywhere and I never noticed.

Here's a link with some more information: https://99percentinvisible.org/article/breakaway-hit-street-...

Another thing to look into if you find that cool is guard rail design. Modern guard rails have some cool features designed to reduce risks associated with hitting them.

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