Hardware and performance

Hi Pham

> I'm using Moodle 1.9

I expected that from the performance figures in your web pages. 1.9 is much more efficient than 2.x. There will be voices saying that 1.9 is not secure, not supported, etc. For you the efficient matters, and 1.9 will get security updates for at least another year. That'll give you some time to test 2.x.

Note: If anybody is tempted to start a discussion on 1.9 vs. 2.0 please do that in the relevent forums, not here!

> I and me know moodle using 1Gb ram for 50 concurrent user.
>
> The system of me have 12Gb ram does must response is 500 concurrent user. However, system current only be used for interval 200 student homework test and interval 700 student view course.

That "50 users per GB" is a very rough formula which just not scale like "500 users per 10 GB". It all depends a) on what those users doing b) what exactly "at the same time" means. You haven't gone through the compulsory documentation given in the introduction to this forum, did you?

Even if a) and b) above are clarified, the performance will just not increase linearly with the amount of RAM, other physical limitations like CPU, network, disk I/O, will stop the progress. In fact I have the feeling that for a single machine your server is performing well.

> I want to optimize the system to service more students most.
>
> I tried configuring the my.cnf mysql but that is not very effective.
>
> Next time, number of students enrolling in our will to about 20,000 and about 2,000 students will have concurrent access.
>
> How to develop a new system for the 2000 concurrent user.

If you have reached the physical limits of a single machine just optimizing is of no use, you will have to consider clustering. There is no suggested "Moodle cluster", search the forum for other people's solutions (the link to the search facility is in the introduction).