question on hosting and memory

[David Banning]

I am running apache 1.3 with php and I find when that for each person 
who visits the site, an additional 29 meg is consumed of my measly 512M.
Searching around, it seems like this is relatively normal.

So here is my question. How do big-time servers handle these type of 
memory requirements? Presumably there are servers out there getting
thousands of visitors at once. Do they have 29 Meg * 1000 for every
thousand visitors? At what memory ceiling do they setup another server
machine to handle the load? Wouldn't it require a ton of servers to handle
a load of a thousand visitors?

I am nowhere in this league, but the question comes to mind because it 
seems crazy that 20 visitors to my site can clog things up, simply because
I choose to run apache and php.

I have been looking at lighttpd decrease memory usage, but I require
url rewriting and I find the documentation for lighttpd is lacking
is this area.

Any comments or suggestions are welcome -

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