We are trying to have approximately 180 to 250 students login to Moodle and take a quiz during a class period. However, teachers are reporting that when all the students go to login it takes 5 minutes or longer for them to login at the beginning of the hour. After monitoring the situation I have noticed that the CPU spikes extremely high on the server during this period. (90% CPU average)
The server is running Windows 2003 Server on dual Intel Xeon 2.33 Ghz dual-core processors with 4G of RAM. The RAM usage and the bandwidth graphs all seem normal. Moodle is running on IIS 6.0 and Mysql 5.0.45 is running on the same box and the authentication method is LDAP from Active Directory.
I am running version 1.7.2, but plan on upgrading to 1.8.3 to see if it resolve the issue. I have tried checking “Enable Record Cache” and “Use database for session information” but those also don’t seem to make a difference either. I have looked at few whitepapers on “Maximizing IIS Performance” and have increased the number of worker processes to 4, but that did not seem to help. When I look at Moodle articles on performance there seems to be many different settings to adjust. I have read a few suggestions about installing APC or disabling “Recycle worker processes”. Rather than continuing to try random settings, I was curious to see if anyone had a suggestion on a logical order of further troubleshooting steps to try.
Here is some graphs of data I have been able to collect: