Stack Overflow recently hit 1 million questions and they receive about 60 million page views per month. Stack Overflow runs on only 5 servers. Social bookmarking service Digg.com receives 200 million pageviews per month and runs on 500 servers. Proportionately something seems off according to Joel Spolsky, the co-founder of Stack Overflow.
He tweeted about that issue recently. It turns out the problem Digg was having is that the original version was running on classic LAMP (Linux, Apache HTTP Server, MySQL, and Perl/PHP/Python). Digg had to port their code to Cassandra because 500 servers wouldn’t be able to handle the load of Digg 4, the newest version of the website.
Digg: 200MM page views, 500 servers. Stack Overflow: 60MM page views, 5 servers. What am I missing?