Most of us, including me, have modest Drupal sites.

I got to wondering where are the scaling points of Drupal. It seems that modest PC hardware and Drupal services up to around 50,000 visits/day. More than that would be an excellent problem to have!

It is suggested that for those with moderate amounts of money, one should stay on one machine and buy better gear. A major site runs upwards of 180,000 views/day on Mid size iron without a PHP accelerator: 1 quad core xeon, 2Gb ram, disk type unknown.

Somewhere above 50,000 views/day apparently one should think about scaling out. I loved the Scaling Drupal article. It shows how to go from one box, to two web servers, two webservers and two database servers ... etc.

enjoy!

reference:
How much server do I need:
http://drupal.org/node/87868#comment-160984
5-6 million page views a month:
http://drupal.org/node/88143

scaling drupal - an open-source infrastructure for high-traffic drupal sites
http://www.johnandcailin.com/blog/john/scaling-drupal-open-source-infras...