Too much traffic?

A colleague (domain obfuscated by me) writes:

"Much as we love the idea of higher traffic, the big numbers become less desirable when it becomes clear that there are no actual eyeballs behind many of those visits.

We're seeing a surge in non-human traffic on Domain Online, and are not quite sure what to do about it. These are not day-to-day spikes separated by days of "normal" traffic. Since March of this year, there has been a steady increase in stress on our servers. Four weeks ago, traffic that was already double or triple our "normal" numbers quadrupled. This traffic has been so significant that our webservers (Two IIS servers) have, on occasion, been knocked or nearly-knocked offline.

For the month of May, our Urchin Tracking Monitor, which counts only those sessions and page views from browsers accepting javascript, showed daily traffic at about 35,000 sessions, 3,400,000 hits and 80,000 page views per day. Over the same period our non-UTM stats, which includes traffic of all sorts, show daily traffic of 105,000 sessions, 3,400,000 hits and 1,175,000 page views. Of the total hits we're showing 3,035,000 coming from Robots (63% coming from the Mozilla Compatible agents, 1.3 million identifying themselves as the Googlebot).

We're using a Windows 2003 SQL server database. Our tech folks ruled out the possibility of an SQL injection attack because we weren't getting hit by a single domain range.

Anybody have experience with these kinds of ratios of human-to-non human traffic? Will adding webservers help us? Other solutions?"

Any suggestions would be appreciated.

ep