First of all, I'd like to describe our scenario:
Dedicated physical servers, running Proxmox
1 VM - Linux (Ubuntu) + MySQL 5.7 - 8 cores, 16GB RAM
Approximately 1.000 Students
The /moodle and /moodledata are stored in a NFS Storage (Netapp) that has a very high performance.
Almost all the time, everything is doing great and the performance is very good, but, we have big problem:
Four times during the course, the users need to make a test and all of them access the moodle simultaneously and than, sometimes, the webserver crashes, although the MySQL server continues working like a charm.
The load average on the webserver reach more than 100 and then, everything became unstable.
What can I do to solve this problem? I had some ideas, but I really don't know what is the best way:
-Creating a tmpfs to store caches
-Clustering some webservers
-Improve even more the VM “hardware”
Thank you guys