jfrank's questions

I'm setting up Apache2 as a reverse proxy for a remote site. Let's assume the remote site is http://app.remotesite.com. Here is a snippet from my virtual host config:

ProxyPass /pxy/ http://app.remotesite.com/

So this should take a request like http://app.mysite.com/pxy/search?q=abc, and pass it through as http://app.remotesite.com/search?q=abc.

I am getting a "Bad request" when I try this. Based on the output in /var/log/apache2/error.log, it is doing the proxy correctly, but it looks like when it connects to the remote site it does so with its IP address. If I take that IP address (printed in error.log) and do a request with it, e.g. http://[IP address]/search?q=abc, I get the same "Bad request" error. My hypothesis is that the remote site is relying on the hostname to serve the request properly, but mod_proxy is not sending it over. I know about the ProxyPreserveHost setting, but this is for preserving the original hostname in the proxy request (in this case, app.mysite.com) which is not what I want.

Can anyone suggest a way for me to force mod_proxy to use the remote site's hostname in its request? Or, if my hypothesis does not make sense, point out what else might be going wrong?

I have already selected httperf as the load testing tool to use. I'm trying to figure out some realistic parameters to use, and if I need to use multiple machines to create more simultaneous connections, etc. I've done some basic load testing before but nothing very sophisticated.

The only information I have about the estimated load is that I'd like to be able to handle 3 million hits in a day. Part of my problem is that I don't have a good rule of thumb for how web traffic is "bursty". Clearly, it depends on the specific site and is never the same twice. But, maybe there is a rule of thumb that says, if your average load for a day is X requests per second, then you should plan for Y simultaneous connections and a peak rate of Z requests per second.

I've done a fair bit of searching around, and while I've found a number of explanations of the various load testing tools and their parameters, I've never seen a decent write up of how you can come up with realistic values to use for the parameters.

I have a linux box hosting a pretty low-traffic site. It's an Amazon EC2 "small" instance, running Ubuntu 10.04. When I run "top" on it, I usually see a load of between 2 and 3, which in my experience is pretty high. However, not much seems to really be happening on the machine -- the CPU is almost always idle, and by watching the apache2 access.log file, I can see that not a lot of requests are coming through. How can I figure out what processes are waiting for the CPU, so that I can try to understand why the load metric is so high?