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Is there example of redundant system (mechanical/electric/biological/...) that is "better" than main system.

By better I mean with comparable in most aspects and with higher parameters in crucial aspects than primary system.

(Counterexample: IT field, main SSD storage is very fast, low access time, tape backup is of course more durable but slower in general).

The question is: where should be applicable to have backup/auxiliary system greater than primary.

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  • $\begingroup$ It's not quite clear what the relation between a main and auxiliary system here, especially for those of us without an IT background (which could just be me, for all I know). $\endgroup$ – HDE 226868 Jan 14 '16 at 22:21
  • $\begingroup$ @HDE226868 Car with remote opening, but if it fails you can always open it mechanically(not comfortable but working). Simple duplication of function. Another one: aircraft landing gear (hydraulic/electric/in the end gravity drop). $\endgroup$ – light Jan 14 '16 at 22:23
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    $\begingroup$ Ah, redundancy. Thanks, that clears it up. $\endgroup$ – HDE 226868 Jan 14 '16 at 22:24
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    $\begingroup$ While it is an interesting question, it is very broad. But foremost, it does not have much to do with worldbuilding as it is. Or can you detail the link? $\endgroup$ – clem steredenn Jan 15 '16 at 6:42
  • $\begingroup$ I agree with @HDE226868. Your question is very broad and unfortunately the wording is slippery. The word "better" has different meanings to different people in different contexts. If you are looking for a specific situation, then please ask about that situation. In your counter-example, if the word better is applied to data capacity and longevity, then a tape back is "better." While if you mean speedy access of data, then the SSD storage is "better". $\endgroup$ – Jim2B Jan 15 '16 at 10:45
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I'm sure there are people who might do something like this on rare occasions. It seems naive to assume otherwise. But generally speaking, no. If you're using the "inferior" item, there's a reason.

I know a lot of people who have a nice, fast car they drive on dates, to social gatherings, on a road trip, etc., but drive their $500 clunker back and forth to work, while using their nice car as a "backup" when the clunker inevitably breaks down occasionally. But the fact remains that the clunker is better in one critical area: using it means you aren't devaluing your nice vehicle when you aren't getting anything out of it.

The same thing applies to everything else listed so far.

  • A mistress may be superior to a wife in many respects, but clearly there's some reason the guy is still married. That one respect is the crucial area the mistress is not better. Maybe the wife cooks and the mistress doesn't. Maybe the wife makes six figures a year. Maybe it's just socially acceptable to have a wife and this guy cares about that kind of thing.
  • A 4G modem is technically superior to a 3G modem so it's the default even if actual bandwidth doesn't need it. If reliability were really an issue, they'd switch to the 3G modems as primary. So really, 4G and 3G are comparable in practice, and there's no reason to prefer one over the other.
  • Software developers are using the beta stuff because you can't develop for it unless you use it. Using the current, stable release of a driver for your upcoming software means by the time your software is finished, it's out of date. The beta driver is therefore better in the crucial aspect that it gives your product better longevity.
  • Cloud storage, or other backup devices, are better for reliability, but are worse in crucial aspects like speed, offline availability, latency, etc. Imagine level load times if you were playing a game completely off the cloud.
  • One car may be as fast as 5 horses, but it's not as fast as 50 horses. Also, it might be far more expensive in this village's economy, so they would save it for when it's needed, not just a little nicer.

In all cases, the backup has some critical reason why it's the backup and not the primary.

The only exceptions I can really think of are due to ignorance. A guy with R9 270 and R9 380 graphics cards might stick the 380 in his computer and put the 270 on the shelf as a backup because he assumes higher numbers mean more power, despite the 270 being substantially faster. When we were kids, my sister would pass in 5th gear instead of 4th, because she thought higher gears meant going faster without understanding the difference between top speed and acceleration. The 3G vs. 4G issue could be a result of this: some boss guy assumes 4G must be better and makes people use that instead of the older 3G that's better for their specific application.

Another exception that's not really an exception is laziness. Maybe the new system is faster and would technically save me lots of time in the long run, but I really don't want to bother learning how to use it. So yeah, it's superior in any externally-objective tests, but it's still locally inferior because that requires me to put forth a lot of effort right now, instead of putting in a little more effort each day that adds up to more total effort.

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I can think of a few examples where this does exist:

  • I manage a network of machines with wireless modems. The modems' primary system is a 4G network, but they have 3G as a backup. Our bandwidth needs are low enough that 4G offers no noticeable benefits while 3G is far more reliable (better uptime).

  • Often times in software development, the beta version is the one primarily used, but a glitchy update makes the stable version more useful.

  • Many companies get just as much done in a 4 day work week as they do in 5. This is a back up plan of sorts if, for example, extreme weather causes an unexpected closure.

As for where this should occur, that's another matter. In order for that to make sense, the act of triggering the backup should be a reliable indicator that a better system is needed for the situation. The best hypothetical I can come up with is a peace time guardian bot that, when destroyed, is immediately replaced by the war time model.

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Shared Backup

I think a very applicable place would be where multiple primary systems share an auxiliary system. The pooled resources etc. of the primary owners could all buy a better backup system than any individual owner could afford, and there's just a general assumption that not all the primary systems will fail at once.

I think cloud computing is a good example of this. Many people back up their local files to the cloud, but the cloud is in general more secure, more reliable, better capacity etc.

A more theoretical example, imagine a village with a lot of horses and one shared car. The car is a backup in case anybody's horse is sick or injured, and because it is so much faster it could in one day do the work of maybe 5 horses. However, there are 50 people in the village, so not everybody can use it. Instead, it just serves as a pooled, better auxiliary system.

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  • $\begingroup$ "[for data storage] the cloud is in general more secure, more reliable, better capacity etc." It's also significantly slower (very few people have gigabit-level Internet connections), introduces counterparty risk, puts the data potentially out of your legal control, and so on. Some would argue that this makes the cloud a worse, not better, solution for backups. (Yes, there are mitigative strategies, but so is there for local backup storage as well.) $\endgroup$ – a CVn Jan 15 '16 at 12:48
  • $\begingroup$ @MichaelKjörling That's very fair, yeah. I was just looking for a real-life example of Shared Backup, maybe cloud computing isn't the best one. Any ideas? $\endgroup$ – Cain Jan 15 '16 at 15:13
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The only time that would make any sense to me is if you consider the main systems to be fodder for attacks, such as Chinese hackers, but then it isn't really your 'main' systems in that case.

Backups are just that, backups, and they are there for when the 'good' stuff breaks but you can't afford to be broke down. Most IT systems for places that really care have main and back up the same, sometimes switching back and forth to both ensure that both systems are good and allowing for down time maintenance on both systems.

In military terms, it would be like they used to send in the conscripts first to soften the walls or some other target and then used the well trained troops (who cost more in training) to clean things up, or stop a route.

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  • $\begingroup$ Yes, diaster recovery solutions and fail over to another during planned maintenance may be example. $\endgroup$ – light Jan 14 '16 at 22:36
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I could see this being a system where cost plays a factor. Say, for instance, a type of hybrid car. It has an electric and a gas engine (assuming that in this particular model the gas engine doesn't just run a generator to charge the batteries) which, under most circumstances the electric motor is the primary system. The electric motor is cheaper to use and more efficient, however it is also weaker but under most circumstances sufficient for everyday use. However if the primary electric motor ceases working, the gas engine could take over which may be more powerful, however less efficient and due to gas prices, more expensive to operate.

This could also work in parcel shipping, where under most circumstances the Postal Service is the primary system, but due to a union strike the mailmen are no longer delivering (a system failure). Instead the backup service, FedEx/UPS/DHL/Courier is used. These services are likely faster and "better" at shipping, but much more expensive so used as a backup.

In data this hypothetical could be a system where your company transmits data typically though cable modems at a very affordable rate per G/bit, but the land lines are severed so the backup wireless system is used which has comparable speeds and due to the mobility could be considered "better" but with a much more prohibitive cost per G/bit so it is only used as a backup.

Maybe a lot of situations where technology is in a state of change and the old reliable methods may be cheaper/easier to operate as a primary than the fancy new and expensive technology.

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I think the key difference here is between a backup system (one you use if the primary is unavailable) and a contingency system (one you pull out if the primary isn't up to the task). You only use the contingency system when you have to, because:

  • maybe it's a one-off contingency, or has a long recharge period
  • maybe it costs substantially more per unit of use, or is harder to use
  • maybe there is collateral damage associated with the contingency (another type of cost, I admit)

The contingency then is both worse and better than the primary. Most examples I can think of are military: bringing out the big guns, alternate strategies with higher chances of success but also higher fatalities, diplomacy vs war etc... But there are other examples: I might ride to work, but take the car as a contingency if it rains. Do I take the heavy, powerful laptop, or the lightweight one with better battery life? The well paid, stressful job, or the sea-change?

Coming back to the question more directly: if your redundant system swaps one thing for another thing of the same class, you can compare parameters more-or-less directly. Any time you swap for something in a different different class, parameters of the substitute will be both better and worse, depending on your perspective of which parameters were the important ones in the first place...

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The primary system is well-tested, stable and people know how to fix it if it breaks down.

The secondary system is new, still has quirks, but it is good enough if primary system is not available.

Generally speaking, in this configuration, the primary system will be older, simpler and less performant than the secondary, which will be new, high-power system.

This can also serve as a way to iron-out the quirks of the new system before it is used as full-on replacement for the old system.

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A hybrid car for mostly city / short range travel could be such a system: The main eingine is electric, not very strong, with low to medium endurance, but very low energy consumption.
The backup system, a regular internal combustion engine powered with gasoline, has more power, more endurance, higher energy density in the fuel, but is only used when the primary system is no longer up for the task.

More generalized: Such a system would make perfect sense when normal day to day use requires little power / endurance / whatnot, but you want a lot more punch in rare situations.

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