One of the primary goals of my research on SQLbusRT is finding formulas which can predict the performance, reliability and scalability of the system under development, looking at the scenario it is implemented in.
Ofcourse saying "good performance", "very reliable" and "yes it is scalable" does not suffice. The formulas should provide a meaningful outcome, which is comparable to other outcomes.
I might not be clear to everyone. Let me give an example, using something we always like to talk about: the weather.
We can say the weather is good or bad today, but that is just a personal opinion. If we want to compare todays weather with the weather of tomorrow for instance, we need numbers. We can give useful information on the weather by giving:
- The temperature in Degrees Celcius or Fahrenheit (min, max, current)
- The humidity in %
- The wind speed in km/hour or miles/hour
- ...
The more I read about it on the net, the more questions come in mind. I already found some scientific articles on the web which might help me, but I'm still looking for some more information. Especially scalability is often rather vague.
If someone knows any clear information on this matter, you're heartily invited to post a comment on this issue. You can help me a lot by doing so. All help is very much appreciated.
PS. I know that performance, reliability and scalability might have different meanings in different situations. Therefore, it is good to know that the system under development is a publish subscribe model with history added. You can find images explaining the architecture in my previous posts. Once again, all help is very much appreciated.
2 comments:
Nice Blog and project !
I think an SQLBus with good scalability means that it can increase the number of subscribers and publishers relatively easy without coming to a stop, so basically it degrades slowly with the added components.
If it degrades almost linearly when adding components until a certain point (where that point is high enough to make it function with enough components needed for the system) i would say it is scalable.
But i'm no scalability expert either though.
I don't think you can really make an objective statement about scalability, up until a certain point most systems scale ok and after that point they drop off. So if you can add enough components until you reach that point, the system scales. But your limited by the bandwidth and latency's in your system. But if that's the real bottleneck, you can increase those by going to fiber or special SCI interconnects which can be used for MySQL Cluster.
Just some thoughts ;-)
Scalability can be compared to complexity theory: e.g. the time to complete a calculation can be exponential or lineair to amount of data.
Scalabily can be researched in directions: keep all parameters stable except one, vary this and look to results and determine relation.
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