As you have created plugins like WPMU itself(part of core Wordpress), ProSites and the plugin to split the main Wordpress database into multiple databases- which is running on EduBlogs.org-- I have a question for you.
(1) Can you provide a rough/accurate estimate of the number of pageviews (for all websites in a WPMU install) can be served per month when the WPMU is running on a single server with 512MB RAM, 1 CPU Core, etc.
(2) And how does the number of pageviews that can be served increase when the server's RAM is increased to 1 GB, then 2GB (and correspondingly the number of CPU cores is also increased)?
The above 2 points dealt with the case when the entire WPMU database as well as the PHP wordpress installation are all on the same server.
(3) Now what is the rate at which number of pageviews served monthly increases, for both points 1 and 2 above-- if we also split the MySQL database into multiple databases running on multiple servers? How (at what rate/manner) does the ability to serve more page views increase with increasing number of 'split' MySQL databases(using the WPMU plugin to split the single WPMU database into multiple databases).
I basically am thinking of launching a CMS kind of service-- but I would like to get a fair idea of the kind of pricing I will have to pay for the servers- which depends on the number of pageviews that can be served.
I have settled on pageviews as that seems to be a simple means of measuring ability to serve websites. Also, all static content like images, CSS/JS files will be served from Content Delivery Network- so those files will neither be stored on Wordpress Server nor will those files put any load on the wordpress server.
In case you do not have such accurate or rough estimates to the above questions, kindly advice on how I can measure such metrics myself.