I'm sorry, but I have a hard time believing that anything is harder to scale than Twitter. With an audience of 175 million users, a Twitter field of 140 bytes makes for 22 gigabytes of uncompressed text per person-tweet. If everyone Tweets ten tweets per hour, that's 220 gigabytes. A one-TB HD would only be good for 5 hours or so, meaning Twitter would need to buy a good 3000 hard-drives per year. That's probably more than Amazon has in total.
I was being so extremely sarcastic to show how ridiculous it is to say "harder to scale than Twitter". Of course there are nowhere near 175 million users, of course they don't tweet ten tweets per hour, and of course the tweets aren't uncompressed. My point is that even with all these assumptions, you have a ridiculous lack of scaling problems. My mention of amazon was meant to show that I was absolutely 100% being completely sarcastic when talking about Twitter's "scaling" problems.
I'm assuming you're being sarcastic -- but the "everyone tweets ten Tweets per hour" figure sounds like it's off by at least one (if not 2 or 3) orders of magnitude.
1) there are far fewwer than 175m active users of twitter
2) a tweet compresses to far less than 140 bytes. Text normally compresses to (easily) a third its size
3) Wikipedia says there are some 300 million tweets per day...or 13 gigabytes per day (compressed).
A single 1 TB hard-drive is almost certainly good enough to store a couple of months of tweets. A year of Tweets should fit on a couple of thousand dollasr of hardware.
and 4) I added the Amazon line so that you guys would know I was being absolutely, 100% sarcastic in every way possible. I guess the clue still wasn't enough.
My point is that there are very few things that are as easy to scale as a platform built on sharing 0.13 kilobyte tweets (0.04 KB compressed), in an age where rendering many common front pages requires a browser to download 600-800KB in static and dynamic content. Come on.
Sometimes the Internet gets sarcasm.... and sometimes we fail badly.
600-800KB +++
I was chatting with my brother in law recently about his website (fashion photographer). His homepage was about 5.6MB. When I asked him about it -- he figured it was normal. Sure enough -- he rattled off a few names for me to check. All of them had front-pages >6MB.
You're forgetting about the network effect involved in scaling something like twitter which is commonly overlooked by people judging services like that.
