17 May 2009, 22:27

I have a problem when there are more than 20 users login to mahara from moodle, linux server CUP usage increase up to 90 to 100%, and at same time, mysql traffic graphic chart increase usage as well, and no body can login.

 Is there any body have same problem? and what is the best config for  MySql?

My System: 

Mahara 1.1.1

Moodle 1.9.4

Server: SUSE linux,  2 * P4 CPU, 2G RAM

17 May 2009, 23:09

Hi - like most PHP webapps, Mahara is CPU bound. P4s are quite old CPUs these days. If you only have two, and have 20 concurrent users, with each request taking maybe up to half a second, I'm not surprised things are going slow. Chuck the database in there and you could be having some interesting resource contention problems.

Short answer - your hardware probably isn't enough for 20 users all at once. Though it will probably handle four or five at once OK.

Solution: well even moving the mysql off that machine will help, but not much, as your problem is lack of CPU. Can you get a better server, or more servers?

Other things you can do: gather more info - can you watch 'top' while the server is being hammered and see where the limits are? High CPU constantly? High IOwait? Constant swapping?

18 May 2009, 15:54

I double checked our server, the CPU are 2 * Intel Xeon CPU 5110 @ 1.60GHz.

and yes, High CPU constantly when users keeping login, and High IOwait and Constant swapping.

I can increase CPU to 4. does it make big different? and What's you suggestion? Because we need more than 500 users login at same time eventually.

By the way, where can i find the information about setup cluster servers for Mahara and Moodle?

Thanks

18 May 2009, 18:12

Ah, Xeons are a lot better than P4s.

Constant swapping is bad. This indicates you don't have enough RAM. You might want to look at getting more? How far into swap is the machine - using all of it or just some of it? The swapping will be causing the high iowait.

More CPUs are always good, if you can get them. But I suggest looking at the RAM problem first.

If you want more than 500 users at a time, you have to translate that to concurrent users. Concurrent users == how many requests are happening per second (and it's handy to split that up by PHP files vs. static files). 500 concurrent users is huge, but 500 actual users, with them clicking a new page on average once every 10 seconds, is just 50 concurrent users. You'd still need a cluster for that I think, but the numbers are a lot better.

We don't have any docs about clustering Mahara, it's not like there's something you download and install to make it work. Getting the database onto a different server is easy enough, you just change the dbhost in the config.php and you're done. You can deploy Mahara on multiple webservers, and we have done so before, but it requires setting up load balancing and other such things that are really beyond the scope of Mahara itself.