Required Hardware

LON-CAPA runs on Intel and AMD hardware. The default setup for a LON-CAPA machine is to operate as a dedicated server, and for maintenance reasons, it is recommended to keep it that way.

The most common use of LON-CAPA is online interactive homework in large enrollment (400 students or more) courses. Students are usually working right up to the deadline, and strong peak workloads are to be expected.

A typical $3,000 server machine (Spring 2005) can handle between 15 and 20 transactions (complete homework submissions) per second.

If you are expecting less than 15 transactions per second, one library server (database backend) doubling as access server (session host) will be sufficient. The next upgrade step will be to add two access servers. You can add up to 10 loadbalancing access servers per library server with an almost linear increase of transactions per second. The next upgrade step beyond would be an additional library server.

Recommended specs for library and for access servers are different: access servers should have a relatively high amount of RAM (approx. 4 GB), and processing power (dual processor or dual-core recommended), but can have smaller and slower disk drives. Access servers do not need to be backed up. Library servers should have high disk throughput and capacity (RAID recommended), and backup tapes or backup applications are essential.

The current MSU production setup consists of nine access servers and one library server.

The nine access servers are set up on a round-robin IP scheme as frontline machines, and are accessed by the students for user session. Additional machines in other domains are registered for the LON-CAPA-internal load-balancing scheme to host additional sessions pushed off by the frontline machines in high-load situations.

This layout is designed to handle approx. 3000 students working concurrently, see user statistics for one of the then-five access servers in 2003.

If the price of the hardware for running LON-CAPA seems prohibitive, please consider that one server on a two to three year replacement cycle costs only about 1/20th of a support staff person. Running a course management system in a full production environment for large student numbers is an expensive undertaking.