Hi, I am running Microsoft Windows 2003 Standard, IIS 6.0 on a Intel Xeon and it is connected with a 2mbps connection and hosted at my ISP's datacenter. Running on it is PHP, and MySQL database, with a PHP CMS system, moodle for example, and also a PHP Forum.

Basically I would like to find out how many concurrent connections would my server be able to handle on average? and how much would be maximum?

Also is there some sort of formula which I can use to calculate it myself?

Thanks in advance =)

There is no way to tell. You need to test to find out. Then, of course, there are all kinds of adjustments you can make to improve performance.

Rasmus Lerdorf, the creator of PHP, spoke at php|works conference in Toronto in September. During his address, he demonstrated an example of server optimization; an application running on his laptop (Ubuntu / Apache / PHP / MySQL) went from handling 17 requests per second to handling 1,100 requests per second without any changes to the code, only by tweaking with Apache and MySQL settings...

there is no formula, the best you can do is try doing some stuff with a bandwidth monitor running to see how much bandwidth was used. From there figure out the percentage it was out of the total and that will give you your answer. you also are held to the number of connections you put in when you installed 03 server, the default is 50, so unless you changed that then no matter what you are limited to 50.