On April 26th 2007 Steve Souders wrote:
The user’s proximity to your web server has an impact on response times. Deploying your content across multiple, geographically dispersed servers will make your pages load faster from the user’s perspective. […] Remember that 80-90% of the end-user response time is spent downloading all the components in the page: images, stylesheets, scripts, Flash, etc. […] A content delivery network (CDN) is a collection of web servers distributed across multiple locations to deliver content more efficiently to users.
Steve posted this approx. e^3.25809654 days after(!) we started to use a CDN for our web sites. Just some days later we noticed the desired effect. Our users started to make more and more traffic. The activity grew. Of course a CDN is some kind of luxury but it’s worth to invest into such a service at a special time. And from our point of view we thought it was time to. We were right.
Actually round about 286.356,421^2 objects will be requested per month by our users. More than the half of that (5,4E10 objects) are photos. Small, medium and big sized ones. So each of all photo files we store will be loaded round(pow(2,4.91)) times in a month. That makes a monthly traffic volume of more ore less 265.334.489.612.288 bytes only for these kind of objects. The total traffic of all delivered objects per month is something about 1,402939962446178 times higher.
At high traffic times there are over 110000110101000002 requests per second hitting our CDN and we are happy that our origin servers only get the (5^5)th part of it.
As a side effect we can learn something about the behaviour of our users because the performance graphs can show us for example what they do in the evening. Maybe the Schimanski serials on 26th of July was one of the reasons for the spikes after 8 pm (see graph above) which are nothing else than commercial breaks. Have a break, have a visit at studiVZ.