Apache is a great web server, I use it myself a lot. There is however one huge problem when working with it in big deployments, and that’s the enormous start and reload times when working with many virtual hosts. When using regular web servers you probably don’t have more then 2 or 3 thousand vhosts, but when deploying a cluster of load balanced web servers you can easily handle tens of thousand of them. And that’s where the problem come in.

This very nice excel graph shows the problem quite nicely.

With 2000 vhosts there’s no problem, the start time is around 2 seconds and reload time is around 5 seconds. But with 40 000 of them it’s another story, as you can see.

These tests where performed on a dual xeon server with 2GB of memory and a nice (15krpm, RAID10) SAN backend for storage and no load on the server.

In comparison, Litespeed reloads with 40 000 vhosts in under 5 seconds.