When we try to purge all server caches or try to check out language string in Language customization server load hits the sky and the operation times out. I think the same thing also happened during a plugin upgrade. What happens is that one of the apache processes goes berserk and server load will be like 20 and after a while it goes back to normal.
* Moodledata is located in a mounted NFS share, could that be the problem? We will start to investigate the NFS-performance more closely but I would like to know what you guys think?
* If the NFS-share is the problem wouldn't it be more stuff timing out?
* Are you able to do these kinds of operations live with users logged in to the system?
Apart from what I have described above server performance seems and feels very good. Load is very low on all our involved servers. Memory usage and CPU usage are low. Application node load mostly pends between 0.1 - 0.8 (4 cores -> 4.0).
We are running a fully virtual environment:
Three application nodes with 4 cores each and 8G of RAM.
MySQL server with 4 cores and 12G of RAM
NFS share for moodledata
No. users: ~10000