for a Download Server
Comparing user experience of a download
server connected to a 100MBit and a GigaBit network
In this test up to 250 users download a 1.1 MB file from the web server every 20 seconds. The web server is first connected to the network with its 100Mbit network card. After the first test the server's second Gigabit network card is used and the test is rerun.
1. Test with 100 MBit Network:
With the 100 MBit card we hit the ~97.000 kbit/s barrier for the server bandwidth (as expected) when the ramp test reaches about 200 users. Until about 100 users each user was able to achieve almost the full 100 Mbit bandwidth of his own. With more users the per-user-speed degrades (T1) until with about 200 users the server reaches its 100Mbit/s limit. At this point the requests can't be answered fast enough, requests begin to pile up and the speed per user almost reaches zero. But looking at the request times (T2) the users experience only a little slowdown until about 200 users are active and request come in faster than they can be answered.
2. Test with GigaBit Network:
As expected this test does not hit a limit of the server bandwidth and reached 120 MBit/s. During the complete test the bandwidth available per user is at about 350 MBit/s. The click times (times that each user experienced to download one file) is at about 30ms during the complete test.
With a 100 Mbit connection this server can not support more than 100 users without a deterioration of performance per user. Using a Gigabit network solved the problem.
|~46.000 downloads pageviews per hour
|Maximum Server Bandwidth
|RAMP (number of users increases during the test time)
|Number of Users
|Tested Web Server
|DELL Dimension, 1.5 Ghz Intel P4, 400 MB RAM, Windows 2003 Small Business Server, IIS6 (out-of-the-box installation), 100 MBit/1 GBit Network Card
|DELL Poweredge 750, 2.8 GHz Intel XEON (Hyperthreading), 2 GB RAM, Windows 2003 Server, (out-of-the-box installation) (running Webserver Stress Tool)