Comment by alexeyrybak | Hacker News Reader

Comment by alexeyrybak | Hacker News Reader

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Pardon, are you sure there was anything about being "equally balanced"? Why 100 databases lead to 100 app servers? I'm afraid the key point is missed: in a balanced system, when input load increases, all parts should slow down all together. Means you just need to have a "proper" proportion of resources in various parts of the system. No need to have 100 apps if your MySQL cluster dies only at 25% cpu load on the apps cluster. This might just indicate you better have 25 app servers vs 100 databases, and spend the rest of money proportionally on both clusters (assuming you only have apps and databases). And a good balance also doesnt mean you have perfectly designed or optimized system. These are different things.

"Given [a well-designed/balanced system], the processing power of the application cluster is arguably the most important factor."

That doesn't follow. You can have a well-designed system where the PHP code only contributes 10% latency and resource usage, in which case the PHP code is clearly not the most important factor.

"This might just indicate you better have 25 app servers vs 100 databases and spend the rest of money proportionally on both clusters."

Exactly. What matters is proportion of latency or resource usage contributed by the PHP code, and that can vary a lot between well-designed systems. The property of being "balanced" doesn't automatically make your PHP application cluster "the most important factor".

"The most important" phrase is misleading, I agree. The idea was to underline the importance of cpu resources on apps cluster but not to state it's the most important thing, the main, the one, always. You are correct.

I think I understand what you mean now (by stretching my imagination quite a bit). This was not really conveyed in what I assume is your blog post though.

And regardless of language difficulties on your side (which we should try to overlook), the conclusion that app server performance is more important than database server performance is left completely unfounded.

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