I'm wondering what is the maximum number of concurrent users that a server can handle? I know this is a vague question that depends on the type of server and several other factors, but how would you go about estimating/calculating the capacity of a server?
What factors would it be a function of? e.g. memory, CPU, disk speed, network card, application specs, etc... What factors are at play, and to what relative effect?
Can one physical server handle only tens of concurrent users, or is it in the hundreds, thousands, hundreds of thousands!? Clearly there must be some general limit as to what a server can handle before another one is needed for load-balancing.
What's generally a number of concurrent users that a website has? I'm guessing that even big websites like eBay that have millions of members wouldn't be able to support millions of concurrent users...is this correct?
Out of curiosity, what's a range of concurrent users that websites like the eBays and Amazons and MySpaces of the world have to support? Is it in the tens of thousands, hundreds of thousands, millions, or more?