Hello,
First of all, apologize for my bad English.

I work for a government school dedicated to distance education, the servers that run moodle are insufficient and will collapse with more students in the next moths. We have now a little less than 1500 students, and the enrollment is going to duplicate. The time a student use the LMS are on average 5 hours at a day, they work interactively, watch videos, download and upload files and make tests.

I’m looking for a basic or entry-level cluster configuration. The features must let me add nodes as needed.

Googling I found many options, most of them are commercials and of course beyond the possibilities of the school. Definitely is impossible purchase a turnkey solution.

We work with FOSS and configure our hardware. We have one servers with 16 GB of RAM and another server with the database engine (mysql) with 8 GB of RAM, I think that this combination is inefficient and that several servers with for example 4 GB or RAM for the web’s could be more efficient if them are configured as clusters. Is it true?

We began configuring a mass storage system with Openfiler to store moodledata to alleviate the workload of web server, and configure the access as NFS, the results are disappointing.

Of course for the cluster configuration I have to deal with load balance, high availability, performance and storage and the options are really confusing (LVM, piranha, ultra-monkey, linux-HA, iSCSI, etc.). What are the best combinations, what are easy to maintain, backup and restore? Is there a GUI for configuration and operation? I must make a decision and begin to configure.

Could you help me with suggestions?

Chalinho

For a school ultra high availability and proper load balancing seems like it would be overkill?

For a basic setup you'd just need some (mid-range) web servers running moodle and then a larger database server and shared storage. Basic load balancing could be done at the DNS level. Once you've got that done you can then look at using virtual IPs to prevent problems if a web-server node goes down and perhaps have one of the web-servers running as a hot-spare incase there is a problem with the MySQL server.
Have you posted on the moodle mailing list? There are many large organisations that use it so I'm sure many people already have a solution in relation to this problem. If you don't have the in-house experience to configure something like this then you could probably ask any local linux consulting company.

Regarding the bad performance of NFS, have you tuned it at all? I'm not sure how optimised openfiler is but there are certainly many documents around about basic changes that can be made to dramatically improve NFS performance

chalinho, I was working for a while in a college with 3000+ students and had 2 servers. 1st for email and 2nd for Moodle.
After a while due to high traffic (around 6TB/month) we've got another one and just placed there the videos and just linked those videos on moodle activities. On that server we allow requests only from the 2nd servers IP in order to maximize security.
This plan we save you a lot of money as cluster solutions are quiet expensive. We've got 3 servers (i7, 8GB RAM, 2x750GB drives) for 99 euros each one. Quiet cheap and works fine for over a year now.

The most elegant solution is often the simplist.