Load Balancing IIS. Serving images and simple html from one server and asp.net pages from another

Question

Hello,

we are using windows 2003 server with dual CPU and IIS gets overflown with requests and not able to handle them but at the same time it uses less than 20% of the CPU and less than 40% of ram. When server is not able to serve any requests not only its not possible to browse the site but its not even serving images which are used on our other sites. We are thinking of installing VMWare to have 2 servers on this machine and using one server to serve asp.net pages and the other one to serve images and simple html pages. Do you guys know how we can route image and html pages requests to one server and requests for aspx pages to another?

Any ideas are appreciated.

Thank you, Denis

Answer 1

1. What is the state of the network? 100mb at 100%?
2. In IIS Are you limiting # of connections? are you limiting Bandwidth?
3. Are there Server errors in the server event log?
4. What is you Database Activity? is is the database bottle necking your webserver?
5. is the DB Network util very high as well? do the DB and webserver talk over the same network? some web servers have 2 network cards, the db and webserver should no share the same bandwidth with external traffic, put external traffic on one network and internal comm on a "backend" network
6. Do you have ANY caching enabled? output, data?

You should be sure that proper data caching is used.

http://msdn.microsoft.com/en-us/library/ms972379.aspx

You should try using a CDN ( content delivery network ) or deploy your own CR ( Content Repository ) server, with different urls than you Website:

• www.yoursite.com/index.aspx

your images / css / js can all be servered from a CR server

• www.yourcdn.com/images/bigImage.jpg

or

• cdn.yoursite.com/images/bigImage.jpg

or

• cr.yoursite.com/images/bigImage.jpg

Since your web server CPU util is so low, try adding HTTP compression to lower some of the network util as per David's good comment

Answer 2

BigBlondeViking has a few good points.

But I want to add that putting 2 VM's on the machine probably won't help you much. What we do (and I would recommend to anyone) is have 2 layers of servers:

• Web Server(s) running Apache in the DMZ
  • these serve your images, css, js and other static content
  • does ssl
  • also used as a reverse proxy server (using mod_proxy)
• Application Server(s) running IIS
  • these serve your ASP.NET pages

This helps add a level of scalability and security to your site.

Sample Apache mod_proxy config:

<VirtualHost 555.55.555.555:80>
ServerName domain.com
DocumentRoot c:/docroot

ProxyPass /img !
ProxyPass /js !
ProxyPass /css !
ProxyPass / http://serverA/vdir
ProxyPassReverse / http://serverA/vdir
</VirtualHost>

This will proxy all requests to / and any subdirs except img, js, and css to serverA/vdir

Answer 3

If your network is at 100% and your CPU is at 40% then adding more processing power and/or virtualizing machines isn't going to help. You can either add more bandwidth (how depends on hosting situation) or use a CDN like BigBlondeViking suggests or reduce bandwidth usage on your app (exactly how depends on app). Easiest option is really a CDN in most cases.

Now, once you get this bandwidth bottleneck solved you might start having CPU usage problems as the number of requests you can handle will increase dramatically.