Hi mate,
There is a stress tool at the following URL, the trial version is limited to a maximum of 10 users though, so you might not get the load you need to take the server down.
I think the big question here is where is your site. Is it on a dedicated server or shared hosting? If it's shared hosting, don't even attempt to run a stress test on it unless you want to be kicked from the server.
If it's on a dedicated box, try to run a stress test starting from a low amount of users and keep increasing it. Once you start to get slowdowns, keep increasing it very slightly until you take the server down. For a true stress test, you really do need to take the server down otherwise you will never know what it can take. After a reboot, the server will be fine again.
Also remember that load on a server can vary greatly. If your mail server is on the same box and you get a peak of mail usage at 2pm, you really want to stress test it then as that will simulate a real life scenario. The problem with this is you could lose mail in this case when the server drops so you also want to simulate the mail usage using a mail server stress tester at the same time as hitting the web server.
If you stress test during a normal quiet mail period or when you don't have backups running you don't get the real picture, because you think your server can take 500 connections and then later find out it can only take 100 when everything else is running.
Hope this helps
Wullie
Fresh Look - Quality Coldfusion/Windows Hosting
The pessimist complains about the wind. The optimist expects it to change. The leader adjusts the sails. - John Maxwell
