Here is my two cents….I also would like to start a discussion elsewhere here as to server and EE tuning…and continue it along.
My thoughts is that the amount of Members means little. I am speaking mostly of the Discussion Forum, since that is my primary use. So it is not the amount of members, but the actual USE of the site by both members and non-members. It is also the AGE of the site. Follow me for a minute…..
Even non-members who come to our site tax the server. They search and browse through the threads in our forum, causing LOTS of sql queries, plus the usual php and ad serving, etc.
In addition, I think the the NUMBER OF POSTS and LENGTH OF THREADS can have something to do with it. We have been running the forums for almost 4 years, so there are LOTS of very long threads and hundreds of thousands of posts and replies. I think all of this has to be sorted every time a user does just about anything.
When I first bought EE, I asked whether the Forum ever archived the old threads…..but was told it didn’t. I wonder if such a scheme might not be wise in the future - that, for instance, posts or threads over 2 or 3 years old could be stored in a way that only searches would bring them out (not every listing of every forum or thread).....
I am not a technical person, but that is my off-the-cuff guess at what is causing our server load to increase substantially.
OK, so we use EE on a dedicated Gentoo Box…...dual core 3.0 MHZ - quite a bit of RAM and fast enough connection.
The EE part of the site is seeing as many as 500+ users/guests/visitors at one time. Maybe only 120 are logged in, but they are very busy…clicking around. People tend to hang out and read a lot!
We are seeing from 10,000 to 15,000 visitors per day to the site, and up to 75,000 page views (mostly EE, some static).
The UNIX server load specs are running from 2 to 4…and sometimes to 5, but assuming that we have dual cores (if they count as 2), that means a very doable load.
If I read the charts correctly, we have about 10 gigs a day being served out - and no big files, mostly the forums.
Hopefully that will give you a handle on what we are doing in terms of a medium scale.