Taking daily pageviews and dividing it by 24 * 60 * 60 assumes your traffic curve isn't a curve at all - it's flat. For your average US-based consumer web app it's highly unlikely to have just as many people using your app at 3am as you do 3pm.
When scaling a web app, you need to prepare for peak usage, not average usage.
Here are a few first-hand examples. Friends for Sale, a social game, had ~10M daily pageviews (100 req/sec avg) but had peak load of > 200 req/sec. Ideeli, a "flash sale" designer shopping site, typically had peak load 5x-20x higher than median load.
Regardless of what Quora's traffic curve looks like, wheels' point still stand - it doesn't matter what backend you're using for 60k users on a web app.
Peak on a decent traffic site will be roughly 2x-3x the average. 5x-20x would be a blog that gets 10 visitors a day and after being posted on news.yc gets 100 visitors.
When scaling a web app, you need to prepare for peak usage, not average usage.
Here are a few first-hand examples. Friends for Sale, a social game, had ~10M daily pageviews (100 req/sec avg) but had peak load of > 200 req/sec. Ideeli, a "flash sale" designer shopping site, typically had peak load 5x-20x higher than median load.
Regardless of what Quora's traffic curve looks like, wheels' point still stand - it doesn't matter what backend you're using for 60k users on a web app.
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http://highscalability.com/friends-sale-architecture-300-mil...